[Mesa-stable] cherry-pick request ffeb77c7 for 10.2 and 10.3 branches

[Roland Scheidegger]

The following commit should be added to 10.2 and 10.3 branches, I forgot
about it when I commited it, it fixes
https://bugs.freedesktop.org/show_bug.cgi?id=83570 (which I forgot to
mention in the commit message too...)

commit ffeb77c7b0552a8624e46e65d6347240ac5ae84d
Author: rconde <rconde01 at outlook.com>
Date:   Wed Sep 17 18:30:23 2014 +0200

gallivm,tgsi: fix idiv by zero crash

While the result of signed integer division by zero is undefined by glsl
(and doesn't exist with d3d10), we must not crash, so need to make sure
we don't get sigfpe much like udiv already does.
Unlike udiv where we return 0xffffffff (as required by d3d10) there is
no requirement right now to return anything specific so we use zero.


Roland