Add x86_cpu_enable_sse2 in cpu_features.c. Update external symbols for
the new name exposed x86_cpu_enable_sse2.

Also, add cpu_check_features to the symbols list (was missing and it's
defined as a ZLIB_INTERNAL symbol).

Bug: 1072308
Change-Id: Ibedfdb0c2e17a20b6f09f49b43ef383b0aa3029b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2156328


Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#760858}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: aba86d62e3b8524f2520ad8797900fbe2f7a55ba