Add a macro for querying the byte order of SkPMColor.

include/core/SkPostConfig.h

Index: include/core/SkPostConfig.h
===================================================================
--- include/core/SkPostConfig.h	(revision 8061)
+++ include/core/SkPostConfig.h	(working copy)
@@ -187,6 +187,26 @@
     #endif
 #endif
 
+/**
+ * SK_PM_BYTE_ORDER_IS can be used to query the byte order of SkPMColor at compile time. E.g.:
+ * #if SK_PM_BYTE_ORDER_IS(B, G, R, A)

[epoger, 2013/03/11 17:26:32]

Clever!!!  Very nice.

+ *     SkDebugf("GDI-compatible SkPMColor");
+ * #endif
+ */
+#ifdef SK_CPU_BENDIAN
+    #define SK_PM_BYTE_ORDER_IS(C0, C1, C2, C3)     \
+        (SK_ ## C3 ## 32_SHIFT == 0  &&             \
+         SK_ ## C2 ## 32_SHIFT == 8  &&             \
+         SK_ ## C1 ## 32_SHIFT == 16 &&             \
+         SK_ ## C0 ## 32_SHIFT == 24)
+#else
+    #define SK_PM_BYTE_ORDER_IS(C0, C1, C2, C3)     \
+        (SK_ ## C0 ## 32_SHIFT == 0  &&             \
+         SK_ ## C1 ## 32_SHIFT == 8  &&             \
+         SK_ ## C2 ## 32_SHIFT == 16 &&             \
+         SK_ ## C3 ## 32_SHIFT == 24)
+#endif
+
 //  stdlib macros
 
 #if 0