Merge #1187 into p/stdenv

Tested building firefox, kdelibs, evince on x86_64-linux.

pkgs/development/libraries/mesa/default.nix

@@ -2,6 +2,7 @@
 , python, libxml2Python, file, expat, makedepend
 , libdrm, xorg, wayland, udev, llvm, libffi
 , libvdpau, libelf
+, grsecEnabled
 , enableTextureFloats ? false # Texture floats are patented, see docs/patents.txt
 , enableExtraFeatures ? false # not maintained
 }:
@@ -41,6 +42,7 @@ stdenv.mkDerivation {
 
   patches = [
     ./static-gallium.patch
+    ./glx_ro_text_segm.patch # fix for grsecurity/PaX
    # TODO: revive ./dricore-gallium.patch when it gets ported (from Ubuntu),
    #  as it saved ~35 MB in $drivers; watch https://launchpad.net/ubuntu/+source/mesa/+changelog
   ];
@@ -79,7 +81,8 @@ stdenv.mkDerivation {
       "--enable-openvg" "--enable-gallium-egl" # not needed for EGL in Gallium, but OpenVG might be useful
       #"--enable-xvmc" # tests segfault with 9.1.{1,2,3}
       #"--enable-opencl" # ToDo: opencl seems to need libclc for clover
-    ];
+    ]
+    ++ optional grsecEnabled "--enable-glx-rts"; # slight performance degradation, enable only for grsec
 
   nativeBuildInputs = [ pkgconfig python makedepend file flex bison ];