spring, warzone2100: work around build problems

I guess there was a slight API change in the last mesa update.

pkgs/games/spring/default.nix

···
   # reported upstream http://springrts.com/mantis/view.php?id=4305
   #enableParallelBuilding = true; # occasionally missing generated files on Hydra
 
+  NIX_CFLAGS_COMPILE = "-fpermissive"; # GL header minor incompatibility
+
   postInstall = ''
     wrapProgram "$out/bin/spring" \
       --prefix LD_LIBRARY_PATH : "${stdenv.gcc.gcc}/lib64:${stdenv.gcc.gcc}/lib::${systemd}/lib"

pkgs/games/warzone2100/default.nix

···
                       --replace "which %s" "${which}/bin/which %s"
   '';
   configureFlags = "--with-backend=qt --with-distributor=NixOS";
+
+  NIX_CFLAGS_COMPILE = "-fpermissive"; # GL header minor incompatibility
+
   postInstall = []
     ++ stdenv.lib.optional withVideos "cp ${sequences_src} $out/share/warzone2100/sequences.wz";
   meta = {