Add back a dummy arc4random_stir for compatibility.

The current arc4random implementation stirs itself as needed, but we
need to keep an arc4random_stir symbol around for binary compatibility.

(cherry-pick of 1e010d60397db706cd3d1c4d5701a2bced441aa8.)

Bug: 17291075
Change-Id: Iaf6171c3ec65c39c1868364d5b35ea280e29a363
1 file changed