Avoid wrong memory access due to double substitution and %%

tools/render_pictures_main.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "LazyDecodeBitmap.h"
 #include "CopyTilesRenderer.h"
 #include "SkBitmap.h"
@@ skipping 381 matching lines @@
             }
         } while(iter.next(&inputFilename));
     } else if (SkStrEndsWith(input, ".skp")) {
         SkString inputPath(input);
         if (!render_picture(inputPath, writePath, mismatchPath, renderer, jsonSummaryPtr)) {
             ++failures;
         }
     } else {
         SkString warning;
         warning.printf("Warning: skipping %s\n", input);
-        SkDebugf(warning.c_str());
+        SkDebugf("%s", warning.c_str());
     }
     return failures;
 }
 
 int tool_main(int argc, char** argv);
 int tool_main(int argc, char** argv) {
     SkCommandLineFlags::SetUsage("Render .skp files.");
     SkCommandLineFlags::Parse(argc, argv);
 
     if (FLAGS_readPath.isEmpty()) {
@@ skipping 91 matching lines @@
         jsonSummary.writeToFile(FLAGS_writeJsonSummaryPath[0]);
     }
     return 0;
 }
 
 #if !defined SK_BUILD_FOR_IOS
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif