This reverts commit 575c09b1.

Reason for revert: Broke the tree, see:

https://ci.chromium.org/p/chromium/builders/ci/Linux%20Builder%20%28dbg%29%2832%29/123424

Original change's description:
> Roll sysroots
> 
> Also needed is [1] in webrtc, which fixes some build warnings. Could
> land in parallel.
> 
> [1] https://webrtc-review.googlesource.com/c/src/+/156980
> 
> BUG=1012850
> 
> Change-Id: Ia24e490db5e71cf1add0e10f4c1264aefb69143c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1859935
> Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#705589}

TBR=dpranke@chromium.org,thomasanderson@chromium.org

Change-Id: Ie1db662441a263452dfe433169b5aa900500744a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1012850
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1860141Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705593}