Adding mheikal@ as an OWNERS in android build related directories

Added myself as an OWNER in directories where I have enough experience
in the contents of the file to review changes.

Change-Id: I7f956ddd44b2f8719f197f7794b5fc9096ba3c48
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2073143
Commit-Queue: Mohamed Heikal <mheikal@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744698}

build/android/OWNERS

 jbudorick@chromium.org
+mheikal@chromium.org
 pasko@chromium.org
 tiborg@chromium.org
 wnwen@chromium.org

third_party/android_deps/OWNERS

 agrieve@chromium.org
 jbudorick@chromium.org
+mheikal@chromium.org
 smaier@chromium.org
 wnwen@chromium.org