mesa: Don't flatten IF statements by default.
MaxIfDepth of 0 means "flatten all the time", not "never flatten".
This is only desirable on hardware that can't support control flow;
software rasterization and most hardware drivers want this.
This alters behavior for swrast as well as i915. Tested on i915.
NOTE: This is a candidate for stable release branches.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
(cherry picked from commit
56705cd36bf48d5050ac9ec10d91fd097a577f42)