This changes libyuv to use the DEPS file for pulling
down all dependencies (thus no Chromium checkout is needed any more).

Add tools_libyuv directory to contain libyuv-specific tools
(needed to avoid name collision with the now DEPSed tools/ directory
of Chromium, which is needed by the toolchain).
Add tools_libyuv/autoroller/roll_deps.py script to automatically
roll all entries in the DEPS file (copied from WebRTC).

third_party/ is now DEPSed as well, including the gtest configuration
headers that used to live inside the libyuv repo.

Add PRESUBMIT.py with a few simple checks + execution of PyLint and
Python unit tests. For PyLint a pylintrc file was also added.

Valgrind in tools_libyuv/valgrind was updated to make PRESUBMIT.py pass
and remove old tsan suppressions (not used).

Removed util/android/test_runner.py since it's no longer needed.

Buildbot changes in https://chromium-review.googlesource.com/436464 
are needed for the Memcheck bot to go green.

BUG=libyuv:676
NOTRY=True

Change-Id: Ib86fea2905a1656bba2933703ce5a59d29d8db6b
Reviewed-on: https://chromium-review.googlesource.com/436264
Commit-Queue: Henrik Kjellander <kjellander@chromium.org>
Reviewed-by: Frank Barchard <fbarchard@google.com>

Fixed invalid references left from
the copied gyp_webrtc.

This CL will also add svn:ignore on a
bunch of directories to speed up builds
(less unnecessary delete + redownload).

It also adds the executable bit to
gyp_libyuv.

R=fbarchard@google.com

Review URL: https://webrtc-codereview.appspot.com/10889004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@992 16f28f9a-4ce2-e073-06de-1de4eb20be90

Download and use GN similar to how WebRTC uses it
for GYP/ninja generation
Similar changes as done in
https://webrtc-codereview.appspot.com/6939004

Add support for VS2013 compilation using the
Chromium standalone toolchain. Similar changes:
https://webrtc-codereview.appspot.com/9769004

Fix the valgrind wrapper script similar to
https://webrtc-codereview.appspot.com/5589006
https://webrtc-codereview.appspot.com/6939004

Remove no longer needed cygwin mount hook.

TEST=All trybots except iOS are passing.
Those will have to be fixed in a future CL.
BUG=310
TESTED=gclient sync on osx/ios
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/10849004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@991 16f28f9a-4ce2-e073-06de-1de4eb20be90