Revert "chromium: Force -fno-stack-protector..."

This reverts commit b7cbb4da11.

The main reason behind this - apart from looking ugly - is that it didn't really
solve anything, see:

http://hydra.nixos.org/build/4198299

So, we need a different and less hacky approach...

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/applications/networking/browsers/chromium/default.nix

@@ -223,6 +223,4 @@ in stdenv.mkDerivation rec {
     license = licenses.bsd3;
     platforms = platforms.linux;
   };
-} // optionalAttrs only25 {
-  NIX_CFLAGS_COMPILE = "-fno-stack-protector";
 }