Running
Fedora Core 3 x86_64
PHP 4.3.11
GCC 4.0

Trying to install dbg-2.11.32.
Getting this error:

configure: creating libtool
appending configuration tag "CXX" to libtool
checking for ld used by g++... /usr/bin/ld -m elf_x86_64
checking if the linker (/usr/bin/ld -m elf_x86_64) is GNU ld... yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking for g++ option to produce PIC... -fPIC
checking if g++ PIC flag -fPIC works... yes
checking if g++ supports -c -o file.o... yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
appending configuration tag "F77" to libtool
configure: creating ./config.status
config.status: creating config.h
config.status: config.h is unchanged
/bin/sh /usr/local/src/dbg-2.11.32/libtool --mode=compile gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -DHAVE_CONFIG_H -DHAVE_CONFIG_H -c /usr/local/src/dbg-2.11.32/dbg_cmd.c -o dbg_cmd.lo
gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -DHAVE_CONFIG_H -DHAVE_CONFIG_H -c /usr/local/src/dbg-2.11.32/dbg_cmd.c -fPIC -DPIC -o .libs/dbg_cmd.o
/usr/local/src/dbg-2.11.32/dbg_cmd.c: In function 'dbg_get_context_sym_table':
/usr/local/src/dbg-2.11.32/dbg_cmd.c:575: error: invalid lvalue in assignment
make: *** [dbg_cmd.lo] Ошибка 1

--------------------------------------cut here---------------------------

Any ideas?

config.status: creating config.h
config.status: config.h is unchanged
^^^^^^^^^^^
means you are running not the first time.
Remove all created files, or unpack fresh sources and run again.

Most probably you forgot to install php-devel package.
Anyway, I'd highly recommend to compile dbg with official php sources available from php.net.

bash-3.00# ./configure
checking build system type... x86_64-redhat-linux-gnu
checking host system type... x86_64-redhat-linux-gnu
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ANSI C... none needed
checking whether gcc and cc understand -c and -o together... yes
checking if compiler supports -R... no
checking if compiler supports -Wl,-rpath,... yes
checking for PHP prefix... /usr
checking for PHP includes... -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend
checking for PHP extension directory... /usr/lib64/php4
checking for re2c... exit 0;
checking for gawk... gawk
checking whether to enable dbg (PHP script debugger) extension... yes, shared
DBG (extension-shared==yes).
no
no
checking for a sed that does not truncate output... /bin/sed
checking for egrep... grep -E
checking for ld used by gcc... /usr/bin/ld
checking if the linker (/usr/bin/ld) is GNU ld... yes
checking for /usr/bin/ld option to reload object files... -r
checking for BSD-compatible nm... /usr/bin/nm -B
checking whether ln -s works... yes
checking how to recognise dependent libraries... pass_all
checking how to run the C preprocessor... gcc -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking dlfcn.h usability... yes
checking dlfcn.h presence... yes
checking for dlfcn.h... yes
checking for g++... g++
checking whether we are using the GNU C++ compiler... yes
checking whether g++ accepts -g... yes
checking how to run the C++ preprocessor... g++ -E
checking for g77... no
checking for f77... no
checking for xlf... no
checking for frt... no
checking for pgf77... no
checking for fort77... no
checking for fl32... no
checking for af77... no
checking for f90... no
checking for xlf90... no
checking for pgf90... no
checking for epcf90... no
checking for f95... no
checking for fort... no
checking for xlf95... no
checking for ifc... no
checking for efc... no
checking for pgf95... no
checking for lf95... no
checking for gfortran... no
checking whether we are using the GNU Fortran 77 compiler... no
checking whether accepts -g... no
checking the maximum length of command line arguments... 32768
checking command to parse /usr/bin/nm -B output from gcc object... ok
checking for objdir... .libs
checking for ar... ar
checking for ranlib... ranlib
checking for strip... strip
checking if gcc static flag works... yes
checking if gcc supports -fno-rtti -fno-exceptions... no
checking for gcc option to produce PIC... -fPIC
checking if gcc PIC flag -fPIC works... yes
checking if gcc supports -c -o file.o... yes
checking whether the gcc linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking whether -lc should be explicitly linked in... no
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
configure: creating libtool
appending configuration tag "CXX" to libtool
checking for ld used by g++... /usr/bin/ld -m elf_x86_64
checking if the linker (/usr/bin/ld -m elf_x86_64) is GNU ld... yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking for g++ option to produce PIC... -fPIC
checking if g++ PIC flag -fPIC works... yes
checking if g++ supports -c -o file.o... yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
appending configuration tag "F77" to libtool
configure: creating ./config.status
config.status: creating config.h
bash-3.00# make
/bin/sh /usr/local/src/dbg-2.11.32/libtool --mode=compile gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -g -O2 -c /usr/local/src/dbg-2.11.32/dbg.c -o dbg.lo
mkdir .libs
gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -g -O2 -c /usr/local/src/dbg-2.11.32/dbg.c -fPIC -DPIC -o .libs/dbg.o
/usr/local/src/dbg-2.11.32/dbg.c: In function 'dbg_startup':
/usr/local/src/dbg-2.11.32/dbg.c:518: warning: cast from pointer to integer of different size
/usr/local/src/dbg-2.11.32/dbg.c: In function 'dbg_shutdown':
/usr/local/src/dbg-2.11.32/dbg.c:537: warning: cast from pointer to integer of different size
/bin/sh /usr/local/src/dbg-2.11.32/libtool --mode=compile gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -g -O2 -c /usr/local/src/dbg-2.11.32/dbg_cmd.c -o dbg_cmd.lo
gcc -I. -I/usr/local/src/dbg-2.11.32 -DPHP_ATOM_INC -I/usr/local/src/dbg-2.11.32/include -I/usr/local/src/dbg-2.11.32/main -I/usr/local/src/dbg-2.11.32 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -DHAVE_CONFIG_H -g -O2 -c /usr/local/src/dbg-2.11.32/dbg_cmd.c -fPIC -DPIC -o .libs/dbg_cmd.o
/usr/local/src/dbg-2.11.32/dbg_cmd.c: In function 'dbg_get_context_sym_table':
/usr/local/src/dbg-2.11.32/dbg_cmd.c:575: error: invalid lvalue in assignment
make: *** [dbg_cmd.lo] Ошибка 1
bash-3.00# yum list installed php-devel
Installed Packages
php-devel.x86_64 4.3.11-2.5 installed
bash-3.00#