Revert of Temporarily suppress -Wunused-function for leveldb. (patchset #1 id:1 of https://codereview.chromium.org/1397833003/ )
Revert of Temporarily suppress -Wunused-function for leveldb. (patchset #1 id:1 of https://codereview.chromium.org/1397833003/ )

Reason for revert:
Hopefully no longer needed.

Original issue's description:
> Temporarily suppress -Wunused-function for leveldb.
>
> Technically this isn't needed in gyp because of issue 503241. Since this
> hopefully won't be needed for long, only do this in gn for this reason.
>
> BUG=505316
> R=hans@chromium.org
>
> Committed: https://chromium.googlesource.com/chromium/src/+/ca225acb9629db8d8060522314b9c1594f0d7d8e

TBR=hans@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=505316

Review URL: https://codereview.chromium.org/1407003006

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#354528}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk