Revert of [build] Switch off warning on gcc bots. (patchset #2 id:20001 of https://codereview.chromium.org/2425913002/ )

Reason for revert:
Seems to be the wrong flag:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Mips%20-%20builder/builds/4709

Original issue's description:
> [build] Switch off warning on gcc bots.
>
> Switch off maybe-uninitialized warning as it gives often
> false positives with optimizations in gcc.
>
> NOTRY=true
> TBR=bmeurer@chromium.org, zhengxing.li@intel.com, caitp@igalia.com, ahaas@chromium.org
>
> Committed: https://crrev.com/0ef0d5b2b8cffd1e3647d79c5ba19752bbbc469c
> Cr-Commit-Position: refs/heads/master@{#40382}

TBR=bmeurer@chromium.org,zhengxing.li@intel.com,caitp@igalia.com,ahaas@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2422103006
Cr-Commit-Position: refs/heads/master@{#40385}