Fix worker race condition in gemmlowp.

Bug: 29993722

  - Merge upstream change 67949d5f0f0e00d44709570d87f5ffa43b81e4f1
  - Fix race condition by adding explicit memory barriers

Change-Id: Ie3e72ac3307e6b205d9f473aac3eb19ea43866f8
(cherry picked from commit d2f96f0c9363004d5bd8d042dbc70c1519875d33)
1 file changed