nir: Add a bunch of algebraic optimizations on logic/bit operations.

nir: Add a bunch of algebraic optimizations on logic/bit operations.

Matt and I noticed a bunch of "val <- ior a a" operations in a shader,
so we decided to add an algebraic optimization for that.  While there,
I decided to add a bunch more of them.

v2: Delete bogus fand/for optimizations (caught by Jason).

total NIR instructions in shared programs: 2023511 -> 2020814 (-0.13%)
NIR instructions in affected programs:     149634 -> 146937 (-1.80%)
helped:                                    1032

total i965 instructions in shared programs: 6035392 -> 6035397 (0.00%)
i965 instructions in affected programs:     537 -> 542 (0.93%)
HURT:                                       2

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>