Fix warning about non-local anonymous struct



git-svn-id: http://skia.googlecode.com/svn/trunk@815 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/GrGpuGL.cpp b/gpu/src/GrGpuGL.cpp
index c3c8f18..8cfc4a0 100644
--- a/gpu/src/GrGpuGL.cpp
+++ b/gpu/src/GrGpuGL.cpp
@@ -536,7 +536,7 @@
 static const GLuint UNKNOWN_BITS = ~0;
 
 // defines stencil formats from more to less preferred
-struct {
+static const struct {
     GLenum  fEnum;
     GLuint  fBits;
 } gStencilFormats[] = {