ubsan shift fixes

src/core/SkBitmapProcState_matrixProcs.cpp

Index: src/core/SkBitmapProcState_matrixProcs.cpp
diff --git a/src/core/SkBitmapProcState_matrixProcs.cpp b/src/core/SkBitmapProcState_matrixProcs.cpp
index 1870a0e50e90f896a49c3d57102d426bd628612d..11d8dcf0ceec646b394cd4328a7de017e07995f2 100644
--- a/src/core/SkBitmapProcState_matrixProcs.cpp
+++ b/src/core/SkBitmapProcState_matrixProcs.cpp
@@ -176,7 +176,7 @@ static inline U16CPU fixed_repeat(SkFixed x) {
 #endif
 
 static inline U16CPU fixed_mirror(SkFixed x) {
-    SkFixed s = x << 15 >> 31;
+    SkFixed s = x * (1 << 15) >> 31;
     // s is FFFFFFFF if we're on an odd interval, or 0 if an even interval
     return (x ^ s) & 0xFFFF;
 }