dev-libs/libusb: upgrade from 0.1.12 to 0.1.18

This CL imports libusb 0.1.18 from upstream Gentoo and modifies the
ebuild to use KEYWORDS="*".

BUG=chromium:381299
CQ-DEPEND=CL:202730
TEST=Tested the following:
1. `emerge-$BOARD dev-libs/libusb`
2. `FEATURES=test emerge-$BOARD platform2`
3. Test `mist`, `lsusb`, `servod`.

Change-Id: Ibac67b3019660faf802b6ca80329114ef0c6e5ce
Reviewed-on: https://chromium-review.googlesource.com/202731
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
9 files changed