uninative: Upgrade to 3.8.1 to include libgcc

Including libgcc solves issues with libpthread.

Signed-off-by: Michael Halstead <mhalstead@linuxfoundation.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 36eb4658)
Signed-off-by: Steve Sakoman <steve@sakoman.com>