Use sse4.2 CRC32 instructions to hash when available.

src/pdf/SkPDFGraphicState.h

Index: src/pdf/SkPDFGraphicState.h
diff --git a/src/pdf/SkPDFGraphicState.h b/src/pdf/SkPDFGraphicState.h
index 84491ba0d38d5dbc809133f111ad2dd258e7b35e..49723bd723775c5d83716289c524decff4f496d7 100644
--- a/src/pdf/SkPDFGraphicState.h
+++ b/src/pdf/SkPDFGraphicState.h
@@ -10,7 +10,7 @@
 #define SkPDFGraphicState_DEFINED
 
 #include "SkPDFTypes.h"
-#include "SkChecksum.h"
+#include "SkOpts.h"
 
 class SkPaint;
 class SkPDFCanon;
@@ -63,7 +63,7 @@ public:
     bool operator==(const SkPDFGraphicState& rhs) const {
         return 0 == memcmp(&fStrokeWidth, &rhs.fStrokeWidth, 12);
     }
-    uint32_t hash() const { return SkChecksum::Murmur3(&fStrokeWidth, 12); }
+    uint32_t hash() const { return SkOpts::hash(&fStrokeWidth, 12); }
 
 private:
     const SkScalar fStrokeWidth;