This resolves ninja error on Windows due to recent depot_tools update, since a newer GYP will be synced.
Initially we ran into a compile issue with libvpx: http://code.google.com/p/webm/issues/detail?id=521
The change in libvpx.gyp is needed since the newer version of Clang that
is used with this Chromium revision provides the -fsanitize=address flag
instead of the old (now deprecated) -faddress-sanitizer. Without
disabling them when asan=1, we'll get compile errors for the assembly
offsets generated for Libvpx. See http://crbug.com/159580 for more details.
BUG=libyuv:173
TEST=trybots passing.
Review URL: https://webrtc-codereview.appspot.com/1026004
git-svn-id: http://webrtc.googlecode.com/svn/trunk@3361 4adac7df-926f-26a2-2b94-8c16560cd09d
75ba51938c