fix warning from scalar --> int32 conversion

BUG=

Review URL: https://codereview.appspot.com/7065050

git-svn-id: http://skia.googlecode.com/svn/trunk@7061 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index b8f43d8..d6a6e44 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -360,6 +360,8 @@
     newState.fPoolStartVertex = DEBUG_INVAL_START_IDX;
     newState.fPoolIndexBuffer = (GrIndexBuffer*)DEBUG_INVAL_BUFFER;
     newState.fPoolStartIndex = DEBUG_INVAL_START_IDX;
+#else
+    (void) newState; // silence compiler warning
 #endif
 }