mesa: maintenance 17.1.2 -> 17.1.4

The announcement seems safe, as usual.

Hydra's Darwin machines will be busy for quite some time on staging,
so let me squeeze this, as it will only be mass rebuild on *-linux.

pkgs/development/libraries/mesa/default.nix

@@ -67,7 +67,7 @@ let
 in
 
 let
-  version = "17.1.2";
+  version = "17.1.4";
   branch  = head (splitString "." version);
   driverLink = "/run/opengl-driver" + optionalString stdenv.isi686 "-32";
 in
@@ -82,7 +82,7 @@ stdenv.mkDerivation {
       "ftp://ftp.freedesktop.org/pub/mesa/older-versions/${branch}.x/${version}/mesa-${version}.tar.xz"
       "https://launchpad.net/mesa/trunk/${version}/+download/mesa-${version}.tar.xz"
     ];
-    sha256 = "0937804f43746339b1f9540d8f9c8b4a1bb3d3eec0e4020eac283b8799798239";
+    sha256 = "06f3b0e6a28f0d20b7f3391cf67fe89ae98ecd0a686cd545da76557b6cec9cad";
   };
 
   prePatch = "patchShebangs .";