Move SkPackBits to src/effects.

src/effects/SkPackBits.h

Index: src/effects/SkPackBits.h
diff --git a/include/core/SkPackBits.h b/src/effects/SkPackBits.h
similarity index 96%
rename from include/core/SkPackBits.h
rename to src/effects/SkPackBits.h
index 1e32ee0875508fc43ff44a58e62310eb6fe8d780..f6430faadd4b17165e2144e481e648dd07bde123 100644
--- a/include/core/SkPackBits.h
+++ b/src/effects/SkPackBits.h
@@ -17,7 +17,7 @@ public:
     /** Given the number of 8bit values that will be passed to Pack8,
         returns the worst-case size needed for the dst[] buffer.
     */
-    static size_t ComputeMaxSize8(int count);
+    static size_t ComputeMaxSize8(size_t srcSize);
 
     /** Write the src array into a packed format. The packing process may end
         up writing more bytes than it read, so dst[] must be large enough.