fix undefined signed shifts

include/core/SkTypes.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTypes_DEFINED
 #define SkTypes_DEFINED
 
@@ skipping 272 matching lines @@
 #define SkToBool(cond)  ((cond) != 0)
 
 #define SK_MaxS16   32767
 #define SK_MinS16   -32767
 #define SK_MaxU16   0xFFFF
 #define SK_MinU16   0
 #define SK_MaxS32   0x7FFFFFFF
 #define SK_MinS32   -SK_MaxS32
 #define SK_MaxU32   0xFFFFFFFF
 #define SK_MinU32   0
-#define SK_NaN32    (1 << 31)
+#define SK_NaN32    ((int) (1U << 31))
 
 /** Returns true if the value can be represented with signed 16bits
  */
 static inline bool SkIsS16(long x) {
     return (int16_t)x == x;
 }
 
 /** Returns true if the value can be represented with unsigned 16bits
  */
 static inline bool SkIsU16(long x) {
@@ skipping 402 matching lines @@
 
     void*       fPtr;
     size_t      fSize;  // can be larger than the requested size (see kReuse)
     uint32_t    fStorage[kSize >> 2];
 };
 // Can't guard the constructor because it's a template class.
 
 #endif /* C++ */
 
 #endif