My cravings for utmost optimization put me (again) in trouble!

I'm trying to recompile 1.18.1.2, and it fails. It worked flawlessly for 1.18.0.6, using Henri's make-SL script, but with this source release, something changed and it doesn't link it anymore.
The compilation goes a-ok, but at linking... (my comments in {}'s)
syylk@karis /home/syylk/src > ./make-SL --retry
Compiling the client into /home/syylk/src/SL/build...
scons: Reading SConscript files ...
Building client 1.18.1.2 on i686-linux (releasefordownload)
No CCACHE_DIR set.
scons: done reading SConscript files.
scons: Building targets ...
python /home/syylk/src/SL/scripts/template_verifier.py --mode="development" --cache_master 2>&1
master: http://secondlife.com/app/message_template/master_message_template.msg
current: /home/syylk/src/SL/scripts/messages/message_template.msg
Refreshing master cache from http://secondlife.com/app/message_template/master_message_template.msg
--- PASS ---
Same
{here it confirms that all object files have been correctly compiled:}
scons: `lib_releasefordownload_client/i686-linux/libllcommon.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllmath.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllvfs.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllimagej2coj.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllimage.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllmessage.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllinventory.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllcharacter.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllprimitive.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllrender.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllwindow.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllxml.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/liblscript.a' is up to date.
scons: `linux_crash_logger/linux-crash-logger-i686-bin-globalsyms' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllaudio.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllmedia.a' is up to date.
scons: `lib_releasefordownload_client/i686-linux/libllui.a' is up to date.
{now, the linking into the bin-globalsyms:}
g++ -o newview/secondlife-i686-bin-globalsyms --no-keep-memory --reduce-memory-overheads /home/syylk/src/SL/build/home/syylk/src/SL/indra/i686-linux-client-releasefordownload/newview/head.o {...all the other object files...} -Llib_releasefordownload_client/i686-linux -L/home/syylk/src/SL/libraries/i686-linux/lib_release_client -llscript -lllwindow -lllrender -lllprimitive -lllmedia -lllinventory -lllimage -lllimagej2coj -lllcharacter -lllaudio -lllui -lllxml -lllmessage -lllvfs -lllmath -lllcommon -lresolv -lgtk-x11-2.0 -latk-1.0 -lgmodule-2.0 -lgdk-x11-2.0 -lgdk_pixbuf-2.0 -lpango-1.0 -lpangoft2-1.0 -lpangox-1.0 -lpangoxft-1.0 -lXinerama -lELFIO -lglib-2.0 -lgobject-2.0 -lcurl -lssl -lcrypto -lexpat -laprutil-1 -lapr-1 -lz -lxmlrpc -lfreetype -lSDL -logg -lvorbisenc -lvorbisfile -lvorbis -ldb-4.2 -ljpeg -lopenjpeg -lpng12 -lGL -lGLU -lfmod-3.75
{here the errors, all related to undefined fns:}
/usr/lib/libgtk-x11-2.0.so: undefined reference to 'gdk_cairo_create'
/usr/lib/libgtk-x11-2.0.so: undefined reference to 'gdk_pango_renderer_set_drawable'
/usr/lib/libgtk-x11-2.0.so: undefined reference to 'gdk_cairo_set_source_pixbuf'
/usr/lib/libgtk-x11-2.0.so: undefined reference to 'g_get_user_config_dir'
{...and many, many more}
collect2: ld returned 1 exit status
scons: *** [newview/secondlife-i686-bin-globalsyms] Error 1
scons: building terminated because of errors.
Of course, I have all the correct libs, and correct headers. If I recursively grep for the undefined references both into /usr/include/* and in the libraries subdir of the source tree, I find references to those functions. Somehow, the new compilation doesn't look in the right place, or doesn't include what in the 1.18.0.6 was included.
I'm puzzled. Someone can help? Henri? Tofu?
Thanks in advance.
EDIT: this damn forum doesn't allow long/messy paths. The actual errors are in longer filenames with lots of "\..\" (with slashes in the RIGHT direction), but the forum blocks them. Blah.