Reduce Roboto's footprint by 1012KB.

Update to Roboto version 2.000982, which reduces the footprint of the fonts
by converting the 'post' table to version 3.0, removing extra cmap tables,
removing unreachable glyphs, and compressing various tables by passing the
fonts through the subsetter at:
https://code.google.com/p/noto/source/browse/nototools/subset.py.

The file size is reduced by 16%, changing from 6269KB to 5258KB.

Bug: 15348046
Change-Id: I7daad0ebd30260674259bce37e374b6dc1298493