Use sse4.2 CRC32 instructions to hash when available.

src/core/SkOpts.h

Index: src/core/SkOpts.h
diff --git a/src/core/SkOpts.h b/src/core/SkOpts.h
index 7c6cfb0dfb63ac021dcb3310687c96a43b1dc0a3..44e337d950a0e59bdeaa2d91613a10f24e999518 100644
--- a/src/core/SkOpts.h
+++ b/src/core/SkOpts.h
@@ -65,6 +65,12 @@ namespace SkOpts {
     // Blend ndst src pixels over dst, where both src and dst point to sRGB pixels (RGBA or BGRA).
     // If nsrc < ndst, we loop over src to create a pattern.
     extern void (*srcover_srgb_srgb)(uint32_t* dst, const uint32_t* src, int ndst, int nsrc);
+
+    // The fastest high quality 32-bit hash we can provide on this platform.
+    extern uint32_t (*hash_fn)(const void*, size_t, uint32_t seed);
+    static inline uint32_t hash(const void* data, size_t bytes, uint32_t seed=0) {
+        return hash_fn(data, bytes, seed);
+    }
 }
 
 #endif//SkOpts_DEFINED