Disabling validation of the glyph cache for standard debug builds.

The validation step is adding 50% overhead to the rendering of
text heavy SkPicture files.

Review URL: https://codereview.appspot.com/6856123

git-svn-id: http://skia.googlecode.com/svn/trunk@6635 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/config/SkUserConfig.h b/include/config/SkUserConfig.h
index 430b4dd..2b1be9f 100644
--- a/include/config/SkUserConfig.h
+++ b/include/config/SkUserConfig.h
@@ -71,6 +71,7 @@
     the performance impact. By default these flags are undefined, but can be
     enabled by uncommenting them below.
  */
+//#define SK_DEBUG_GLYPH_CACHE
 //#define SK_DEBUG_PATH
 
 /*  To assist debugging, Skia provides an instance counting utility in