As of https://chromium-review.googlesource.com/#/c/608869/, Chromium is
now using yasm 1.3.0, which means we can rely on it.

This is upstream's yasm-1.3.0-win32.exe which has a SHA-512 hash of:
850b26be5bbbdaeaf45ac39dd27f69f1a85e600c35afbd16b9f621396b3c7a19863ea3ff316b025b578fce0a8280eef2203306a2b3e46ee1389abb65313fb720

(I'm using such a humungous hash because if one searches for it on
Google, there is evidence that someone else in the world downloaded the
same hash.)

Change-Id: I4674080dd07d3e07f399a67e767a00fc67d4aa63
Reviewed-on: https://boringssl-review.googlesource.com/19104
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: Steven Valdez <svaldez@google.com>