glsl: Fix loop bounds detection.

glsl: Fix loop bounds detection.

When analyzing a loop where the loop condition is expressed in the
non-standard order (e.g. "4 > i" instead of "i < 4"), we were
reversing the condition incorrectly, leading to a loop bound that was
off by 1.

Fixes piglit tests {vs,fs}-loop-bounds-unrolled.shader_test.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>