roll libyuv from r1466 to r1474.
roll libyuv from r1466 to r1474.

Contains the following revisions:
https://chromium.googlesource.com/libyuv/libyuv/+log/cda9d38a4..3c4f5735

Summary of changes
Re-enabled LTO for arm llvm.  Bug affects gcc 4.9 but not llvm.
Disable android test runner.
Add I420AlphaToABGR for skcanvas.
Switch clang-cl 32 bit builds to use Visual C source instead of GCC, so that /fallback on any source files, will produce identical results and not a link error.  Contains work arounds for 2 compiler bugs - structure elements can't be used, and tables cant be directly indexed.

BUG=chromium:469376, chromium:267773, libyuv:473, libyuv:487, libyuv:469

Review URL: https://codereview.chromium.org/1318813002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#345721}

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