copy license files to each subdir
copy license files to each subdir

This makes it easier to distribute, and when people only take a subdir
slice of the repo (like hterm/), make sure the license is retained.

Change-Id: Ib4eec0fa809d59565ece79a4c18ee1011ac04728
Reviewed-on: https://chromium-review.googlesource.com/843827
Reviewed-by: Brandon Gilmore <adbfbaf7e4f927b45ce8ad3e5043a632414a833b@google.com>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

chromium/hterm,chromium/hterm,chromium/hterm,chromium/hterm