i965/fs: Reject copy propagation into SEL if not min/max.

i965/fs: Reject copy propagation into SEL if not min/max.

We shouldn't ever see a SEL with conditional mod other than GE (for max)
or L (for min), but we might see one with predication and no conditional
mod.

total instructions in shared programs: 8241806 -> 8241902 (0.00%)
instructions in affected programs: 13284 -> 13380 (0.72%)
HURT: 62

total cycles in shared programs: 84165104 -> 84166244 (0.00%)
cycles in affected programs: 75364 -> 76504 (1.51%)
helped: 10
HURT: 34

Fixes generated code in at least Sanctum 2, Borderlands 2, Goat
Simulator, XCOM: Enemy Unknown, and Shogun 2.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92234
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>