Reland "Roll buildtools and enable in-tree libc++ on Android"

This is a reland of 1a874fe60ccb87401867a7334b8eb11e5e4b1552

Original change's description:
> Roll buildtools and enable in-tree libc++ on Android
>
> Buildtools changelog:
> https://chromium.googlesource.com/chromium/buildtools/+log/7d88270de197ebe8b439ab5eb57a4a2a0bb810e0..0e1cbc4eab6861b0c84bf2ed9a3c4b7aa2063819
>
> BUG=767901
> R=thakis
>
> Change-Id: I96fdafca5e228cbfe7a0909170c0235e7845bbde
> Reviewed-on: https://chromium-review.googlesource.com/c/1385021
> Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#618035}

TBR=thakis

Bug: 767901
Change-Id: Id8645ae0fb1c4801d3ed4a10efd3e91239058163
Reviewed-on: https://chromium-review.googlesource.com/c/1405720
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621915}
2 files changed