* Attempt to fix some ATI driver crash on PostShadowPSSM15

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@7493 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core-data/Common/MatDefs/Shadow/PostShadowPSSM15.frag

@@ -1,4 +1,5 @@
 #extension GL_ARB_texture_gather : enable
+#extension GL_ARB_gpu_shader5 : enable
 
 #ifdef HARDWARE_SHADOWS
     #define SHADOWMAP sampler2DShadow