Zero out GrSamplerState in constructor to recover performance loss on Linux from r4102.
(Noise in padding bytes was breaking operator==())
Visual review by bsalomon@.



git-svn-id: http://skia.googlecode.com/svn/trunk@4108 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/GrSamplerState.h b/include/gpu/GrSamplerState.h
index 4d2d5f2..3cafa45 100644
--- a/include/gpu/GrSamplerState.h
+++ b/include/gpu/GrSamplerState.h
@@ -90,6 +90,7 @@
     , fRadial2Radius0()
     , fRadial2PosRoot()
     , fCustomStage (NULL) {
+        memset(this, 0, sizeof(GrSamplerState));
         this->reset();
     }