replace SkFixedDiv impl with native 64bit math

include/core/SkFixed.h

Index: include/core/SkFixed.h
diff --git a/include/core/SkFixed.h b/include/core/SkFixed.h
index 8cf7a5679ce28358e994114204aba92162bc4332..f920fea7361b6d08312d3900e197ecdc7bfb95b9 100644
--- a/include/core/SkFixed.h
+++ b/include/core/SkFixed.h
@@ -78,7 +78,10 @@ typedef int32_t             SkFixed;
 #define SkFixedAbs(x)       SkAbs32(x)
 #define SkFixedAve(a, b)    (((a) + (b)) >> 1)
 
-#define SkFixedDiv(numer, denom)    SkDivBits(numer, denom, 16)
+static inline int32_t SkFixedDiv(int32_t numer, int32_t denom) {
+    int64_t tmp = ((int64_t)numer << 16) / denom;
+    return (int32_t)tmp;
+}
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////
 // Now look for ASM overrides for our portable versions (should consider putting this in its own file)