Support installing sysroot for mips64el for Linux

Change adds support for installing Debian Stretch sysroot for mips64el.

BUG=751812

Change-Id: Iaa32d0b0701b17a49e0ac735134ad85cf746fe23
Reviewed-on: https://chromium-review.googlesource.com/776873
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517863}
1 file changed