Add johnstiles@ to OWNERS for libpng.

I've volunteered to help with Skia codec work, so having OWNERS
will reduce the review burden for scroggo@.

Change-Id: Iaacc9387a450644b4843b38d0797b66108e94dcb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5453239
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Cr-Commit-Position: refs/heads/main@{#1287443}
NOKEYCHECK=True
GitOrigin-RevId: ec9d7837b77fa09a0fb1a660ef260bbfec0038f9
1 file changed