Revert of Slim Skia down to just one murmur3 implementation.

src/core/SkChecksum.h

Index: src/core/SkChecksum.h
diff --git a/src/core/SkChecksum.h b/src/core/SkChecksum.h
index daf87cf62ea5991d8d2ef3c4b2866c2290de2802..fe1e9584a20e8e87c2475a648af21e03db9e6710 100644
--- a/src/core/SkChecksum.h
+++ b/src/core/SkChecksum.h
@@ -51,10 +51,6 @@
         return hash;
     }
 
-    // Remind compiler that our users will be intentionally violating strict aliasing by casting
-    // their data to const uint32_t*, so don't apply any strict-aliasing-based optimizations.
-    typedef uint32_t SK_ATTRIBUTE(may_alias) FourByteAligned;
-
     /**
      * Calculate 32-bit Murmur hash (murmur3).
      * This should take 2-3x longer than SkChecksum::Compute, but is a considerably better hash.
@@ -65,7 +61,7 @@
      *  @param seed Initial hash seed. (optional)
      *  @return hash result
      */
-    static uint32_t Murmur3(const FourByteAligned* data, size_t bytes, uint32_t seed=0) {
+    static uint32_t Murmur3(const uint32_t* data, size_t bytes, uint32_t seed=0) {
         SkASSERTF(SkIsAlign4(bytes), "Expected 4-byte multiple, got %zu", bytes);
         const size_t words = bytes/4;
 
@@ -98,7 +94,7 @@
      *  @param size Size of the data block in bytes. Must be a multiple of 4.
      *  @return checksum result
      */
-    static uint32_t Compute(const FourByteAligned* data, size_t size) {
+    static uint32_t Compute(const uint32_t* data, size_t size) {
         SkASSERT(SkIsAlign4(size));
 
         /*