Force a re-emerge of host libtool
BUG=chromium-os:37334
TEST=Added fake "4.6.x-google" version string to libtool and ran
./update_chroot and verified libtool was re-emerged
Change-Id: I82d3da181831a7718b230305c5aca7899d591c2d
Signed-off-by: Allen Martin <amartin@nvidia.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/39858
Reviewed-by: Mike Frysinger <vapier@chromium.org>
