Remove pthreads patch, roll in new patches, disable unchecked bit readers.

ffmpeg.gyp

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # There's a couple key GYP variables that control how FFmpeg is built:
 #   ffmpeg_branding
 #     Controls whether we build the Chromium or Google Chrome version of
 #     FFmpeg.  The Google Chrome version contains additional codecs.
 #     Typical values are Chromium, Chrome, ChromiumOS, and ChromeOS.
 #   use_system_ffmpeg
@@ skipping 429 matching lines @@
                          '-i', '<(intermediate_dir)',
                          '-o', '<(output_dir)',
                          '-t', '<(outfile_type)',
                          '<@(RULE_INPUT_PATH)',
               ],
               'message': 'Generating FFmpeg import libraries.',
             },
           ],
 
           # Copy prebuilt binaries to build directory.
-          'dependencies': ['../../build/win/system.gyp:cygwin'],
           'copies': [{
             'destination': '<(PRODUCT_DIR)/',
             'files': [
               'chromium/binaries/<(ffmpeg_bin_dir)/avcodec-53.dll',
               'chromium/binaries/<(ffmpeg_bin_dir)/avformat-53.dll',
               'chromium/binaries/<(ffmpeg_bin_dir)/avutil-51.dll',
             ],
           }],
         }, {  # else OS != "win", use POSIX stub generator
           'variables': {
@@ skipping 86 matching lines @@
                   ],
                 }],
               ],
             }],
           ],  # conditions
         }],
       ],  # conditions
     },
   ],  # targets
 }