SkCodec: add wbmp class

src/utils/SkMD5.h

Index: src/utils/SkMD5.h
diff --git a/src/utils/SkMD5.h b/src/utils/SkMD5.h
index 1834a1b03b312d6185b6a438509dc6aa9767438b..ed557931c242cdb888eefdd57439e0727de26636 100644
--- a/src/utils/SkMD5.h
+++ b/src/utils/SkMD5.h
@@ -36,6 +36,12 @@ public:
 
     struct Digest {
         uint8_t data[16];
+        bool operator ==(Digest const& other) const {
+            return 0 == memcmp(data, other.data, sizeof(data));
+        }
+        bool operator !=(Digest const& other) const {
+            return 0 != memcmp(data, other.data, sizeof(data));
+        }
     };
 
     /** Computes and returns the digest. */