Add hansson to OWNERS for build files

Soong team has cleaned up their OWNERS file, so add back hansson
to the frameworks/base build file owners.

We'll explore migrating all the API related build rules into the
api subdir, which would allow removal from the global file.

Change-Id: Ie9f6a22376b49abec5e45c3b805e00d87361101d
1 file changed