Silence -Wclobbered in each file that needs it.

src/codec/SkPngCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkColorSpace_Base.h"
 #include "SkColorTable.h"
 #include "SkMath.h"
 #include "SkOpts.h"
 #include "SkPngCodec.h"
 #include "SkPoint3.h"
 #include "SkSize.h"
 #include "SkStream.h"
 #include "SkSwizzler.h"
 #include "SkTemplates.h"
 #include "SkUtils.h"
 
+// This warning triggers false postives way too often in here.
+#if defined(__GNUC__) && !defined(__clang__)
+    #pragma GCC diagnostic ignored "-Wclobbered"
+#endif
+
 ///////////////////////////////////////////////////////////////////////////////
 // Callback functions
 ///////////////////////////////////////////////////////////////////////////////
 
 static void sk_error_fn(png_structp png_ptr, png_const_charp msg) {
     SkCodecPrintf("------ png error %s\n", msg);
     longjmp(png_jmpbuf(png_ptr), 1);
 }
 
 void sk_warning_fn(png_structp, png_const_charp msg) {
@@ skipping 837 matching lines @@
     SkCodec* outCodec;
     if (read_header(stream, chunkReader, &outCodec, nullptr, nullptr)) {
         // Codec has taken ownership of the stream.
         SkASSERT(outCodec);
         streamDeleter.release();
         return outCodec;
     }
 
     return nullptr;
 }