Don't unset gFCSafeToUse when it's still safe to use.

src/fonts/SkFontMgr_fontconfig.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFontMgr.h"
 #include "SkFontStyle.h"
 #include "SkFontConfigInterface.h"
@@ skipping 20 matching lines @@
         if (FcGetVersion() < 21091) {  // We assume FcGetVersion() has always been thread safe.
             gFCMutex.acquire();
             fUnlock = true;
         } else {
             fUnlock = false;
         }
         gFCSafeToUse = true;
     }
 
     ~FCLocker() {
-        gFCSafeToUse = false;
         if (fUnlock) {
+            gFCSafeToUse = false;
             gFCMutex.release();
         }
     }
 
 private:
     bool fUnlock;
 };
 
 } // namespace
 
@@ skipping 272 matching lines @@
         FCLocker lock;
         return FontConfigTypeface::LegacyCreateTypeface(NULL, familyName,
                                                   (SkTypeface::Style)styleBits);
     }
 };
 
 SkFontMgr* SkFontMgr::Factory() {
     SkFontConfigInterface* fci = RefFCI();
     return fci ? SkNEW_ARGS(SkFontMgr_fontconfig, (fci)) : NULL;
 }