Re-land with fixes for Android.

We were getting multiply defined symbol errors on Linux for some
stuff in the common sources. Switch to using a static lib target
for the common sources, and also sync BUILD.gn with the latest gyp.

BUG=angle:773

Change-Id: Id3edecc633b1c4be205558137c91baf87f256156
Reviewed-on: https://chromium-review.googlesource.com/240145Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>