fix "libc}/lib" and similar references

Done mostly without any verification.
I didn't bother with libc}/include, as the path is still correct.

pkgs/games/gemrb/default.nix

@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   # TODO: make libpng, libvorbis, sdl_mixer, freetype, vlc, glew (and other gl reqs) optional
 
   # Necessary to find libdl.
-  CMAKE_LIBRARY_PATH = "${stdenv.cc.libc}/lib";
+  CMAKE_LIBRARY_PATH = "${stdenv.cc.libc.out}/lib";
 
   # Can't have -werror because of the Vorbis header files.
   cmakeFlags = "-DDISABLE_WERROR=ON -DCMAKE_VERBOSE_MAKEFILE=ON";