Fix more warnings.

tools/skimage_main.cpp

 /*
  * Copyright 2011 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 "SkColorPriv.h"
 #include "SkCommandLineFlags.h"
@@ skipping 165 matching lines @@
     stream.rewind();
     if (!codec->decode(&stream, &bitmap, SkBitmap::kARGB_8888_Config,
                        SkImageDecoder::kDecodePixels_Mode)) {
         gDecodeFailures.push_back().set(srcPath);
         return;
     }
 
     gSuccessfulDecodes.push_back().printf("%s [%d %d]", srcPath, bitmap.width(), bitmap.height());
 
     if (FLAGS_testSubsetDecoding) {
-        bool couldRewind = stream.rewind();
+        SkDEBUGCODE(bool couldRewind =) stream.rewind();
         SkASSERT(couldRewind);
         int width, height;
         // Build the tile index for decoding subsets. If the image is 1x1, skip subset
         // decoding since there are no smaller subsets.
         if (codec->buildTileIndex(&stream, &width, &height) && width > 1 && height > 1) {
             SkASSERT(bitmap.width() == width && bitmap.height() == height);
             // Call decodeSubset multiple times:
             SkRandom rand(0);
             for (int i = 0; i < 5; i++) {
                 SkBitmap bitmapFromDecodeSubset;
@@ skipping 11 matching lines @@
                         make_outname(&outPath, writePath->c_str(), srcPath, suffix.c_str());
                         SkDEBUGCODE(bool success =)
                         write_bitmap(outPath.c_str(), &bitmapFromDecodeSubset);
                         SkASSERT(success);
                         gSuccessfulSubsetDecodes.push_back().printf("\twrote %s", outPath.c_str());
                         // Also use extractSubset from the original for visual comparison.
                         SkBitmap extractedSubset;
                         if (bitmap.extractSubset(&extractedSubset, rect)) {
                             suffix.printf("_%s_extracted.png", subsetDim.c_str());
                             make_outname(&outPath, writePath->c_str(), srcPath, suffix.c_str());
-                            success = write_bitmap(outPath.c_str(), &extractedSubset);
+                            SkDEBUGCODE(success =) write_bitmap(outPath.c_str(), &extractedSubset);
                             SkASSERT(success);
                         }
                     }
                 } else {
                     gFailedSubsetDecodes.push_back().printf("Failed to decode region %s from %s\n",
                                                             subsetDim.c_str(), srcPath);
                 }
             }
         }
     }
@@ skipping 155 matching lines @@
     }
 
     return failed ? -1 : 0;
 }
 
 #if !defined SK_BUILD_FOR_IOS
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif