Fix intermittent GrAutoLocaleSetter crashes on Windows

src/gpu/GrAutoLocaleSetter.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrAutoLocaleSetter_DEFINED
 #define GrAutoLocaleSetter_DEFINED
 
 #include "GrTypes.h"
 
+#if defined(SK_BUILD_FOR_WIN)
+#include "SkString.h"
+#endif
+
 #if !defined(SK_BUILD_FOR_ANDROID)
 #include <locale.h>
 #endif
 
 #if defined(SK_BUILD_FOR_MAC) || defined(SK_BUILD_FOR_IOS)
 #include <xlocale.h>
 #endif
 
 /**
  * Helper class for ensuring that we don't use the wrong locale when building shaders. Android
  * doesn't support locale in the NDK, so this is a no-op there.
  */
 class GrAutoLocaleSetter : public SkNoncopyable {
 public:
     GrAutoLocaleSetter (const char* name) {
 #if defined(SK_BUILD_FOR_WIN)
-        fOldPerThreadLocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
-        fOldLocale = setlocale(LC_ALL, name);
+        fOldPerThreadLocale = _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);        
+        char* oldLocale = setlocale(LC_ALL, name);
+        if (oldLocale) {
+            fOldLocale = oldLocale;
+            fShouldRestoreLocale = true;
+        } else {
+            fShouldRestoreLocale = false;
+        }
 #elif !defined(SK_BUILD_FOR_ANDROID) && !defined(__UCLIBC__)
         fLocale = newlocale(LC_ALL, name, 0);
         if (fLocale) {
             fOldLocale = uselocale(fLocale);
         } else {
             fOldLocale = static_cast<locale_t>(0);
         }
 #else
         (void) name; // suppress unused param warning.
 #endif
     }
 
     ~GrAutoLocaleSetter () {
 #if defined(SK_BUILD_FOR_WIN)
-        if (fOldLocale) {
-            setlocale(LC_ALL, fOldLocale);
+        if (fShouldRestoreLocale) {
+            setlocale(LC_ALL, fOldLocale.c_str());
         }
         _configthreadlocale(fOldPerThreadLocale);
 #elif !defined(SK_BUILD_FOR_ANDROID) && !defined(__UCLIBC__)
         if (fLocale) {
              uselocale(fOldLocale);
              freelocale(fLocale);
         }
 #endif
     }
 
 private:
 #if defined(SK_BUILD_FOR_WIN)
     int fOldPerThreadLocale;
-    const char* fOldLocale;
+    bool fShouldRestoreLocale;
+    SkString fOldLocale;
 #elif !defined(SK_BUILD_FOR_ANDROID) && !defined(__UCLIBC__)
     locale_t fOldLocale;
     locale_t fLocale;
 #endif
 };
 
 #endif