I decided to compile libobjc2. I checked it out, and just ran make && sudo make install.
sudo make uninstall ; make clean ; CC=gcc-4.6 CXX=g++-4.6 ./configure ; make ; sudo make install
ivucica@theevilmacbook:~/Programs/gnustep/modules/core/base$ make
This is gnustep-make 2.6.0. Type 'make print-gnustep-make-help' for help.
Making all in Source ...
Making all in Additions ...
Making all for subproject Additions...
make[4]: Nothing to be done for `internal-subproject-compile'.
Making all in subprojects of library libgnustep-base...
Making all for subproject ObjectiveC2...
make[5]: Nothing to be done for `internal-subproject-compile'.
Making all for subproject Additions...
make[5]: Nothing to be done for `internal-subproject-compile'.
Making all for subproject unix...
make[5]: Nothing to be done for `internal-subproject-compile'.
Making all for library libgnustep-base...
make[4]: Nothing to be done for `internal-library-compile'.
Making all in SSL ...
make[2]: Nothing to be done for `internal-master-bundle-all'.
Making all in Tools ...
Making all for tool autogsdoc...
Linking tool autogsdoc ...
../Source/./obj/libgnustep-base.so: undefined reference to `__objc_uninstalled_dtable'
../Source/./obj/libgnustep-base.so: undefined reference to `objc_mutex_lock'
../Source/./obj/libgnustep-base.so: undefined reference to `sel_getTypeEncoding'
../Source/./obj/libgnustep-base.so: undefined reference to `objc_mutex_unlock'
../Source/./obj/libgnustep-base.so: undefined reference to `objc_setUncaughtExceptionHandler'
../Source/./obj/libgnustep-base.so: undefined reference to `sel_getTypedSelector'
../Source/./obj/libgnustep-base.so: undefined reference to `__objc_update_dispatch_table_for_class'
collect2: ld returned 1 exit status
make[4]: *** [obj/autogsdoc] Error 1
make[3]: *** [internal-tool-all_] Error 2
make[2]: *** [autogsdoc.all.tool.variables] Error 2
make[1]: *** [internal-all] Error 2
make: *** [internal-all] Error 2