Annotate SK_COMPILE_ASSERT's typedef as permissibly unused, to fix GCC 4.8 build warning. Patch ori…

include/core/SkPostConfig.h

Index: include/core/SkPostConfig.h
diff --git a/include/core/SkPostConfig.h b/include/core/SkPostConfig.h
index 022757554cc1739245f6aa8b8580a93478be984f..07c1217f4f0ea09846fbd07ee6233202f54398ec 100644
--- a/include/core/SkPostConfig.h
+++ b/include/core/SkPostConfig.h
@@ -63,6 +63,14 @@
     #endif
 #endif
 
+#if !defined(SK_ATTRIBUTE)
+    #if defined(__clang__) || defined(__GNUC__)
+        #define SK_ATTRIBUTE(attr) __attribute__((attr))
+    #else
+        #define SK_ATTRIBUTE(attr)
+    #endif
+#endif
+
 #if !defined(SK_SUPPORT_GPU)
     #define SK_SUPPORT_GPU 1
 #endif
@@ -354,6 +362,12 @@
 
 //////////////////////////////////////////////////////////////////////
 
+#if !defined(SK_UNUSED)
+    #define SK_UNUSED SK_ATTRIBUTE(unused)
+#endif
+
+//////////////////////////////////////////////////////////////////////
+
 #ifndef SK_PRINTF_LIKE
 #if defined(__clang__) || defined(__GNUC__)
 #define SK_PRINTF_LIKE(A, B) __attribute__((format(printf, (A), (B))))