Upstream did this in 609b0852e4 and it's
easier to apply patches if we do also.

Change-Id: I5142693ed1e26640987ff16f5ea510e81bba200e
Reviewed-on: https://boringssl-review.googlesource.com/13771
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

Upstream added new instructions in
f4d456408d and
4e3d2866b6.

Change-Id: I835650426a0dffca2d8686d64aef99097a4bd186
Reviewed-on: https://boringssl-review.googlesource.com/8520
Reviewed-by: Adam Langley <agl@google.com>

Although x86masm.pl exists, upstream's documentation suggest only x86nasm.pl is
supported. Yasm seems to handle it fine with a small change.

Change-Id: Ia77be57c6b743527225924b2b398f2f07a084a7f
Reviewed-on: https://boringssl-review.googlesource.com/2092
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)