nir/algebraic: Simplify some comparisons like a+constant < constant

nir/algebraic: Simplify some comparisons like a+constant < constant

v2: Remove unsafe integer versions of the optimizations.  This change
had no effect on shader-db results.  Suggested by Caio.

All Gen6+ platforms had similar results. (Ice Lake shown)
total instructions in shared programs: 16333713 -> 16332631 (<.01%)
instructions in affected programs: 258112 -> 257030 (-0.42%)
helped: 1275
HURT: 407
helped stats (abs) min: 1 max: 7 x̄: 1.17 x̃: 1
helped stats (rel) min: 0.20% max: 8.33% x̄: 1.33% x̃: 0.86%
HURT stats (abs)   min: 1 max: 2 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.11% max: 2.94% x̄: 0.98% x̃: 0.98%
95% mean confidence interval for instructions value: -0.70 -0.59
95% mean confidence interval for instructions %-change: -0.84% -0.70%
Instructions are helped.

total cycles in shared programs: 367596791 -> 367601268 (<.01%)
cycles in affected programs: 3420062 -> 3424539 (0.13%)
helped: 1553
HURT: 783
helped stats (abs) min: 1 max: 742 x̄: 24.36 x̃: 6
helped stats (rel) min: 0.05% max: 21.12% x̄: 1.47% x̃: 0.65%
HURT stats (abs)   min: 1 max: 557 x̄: 54.04 x̃: 14
HURT stats (rel)   min: 0.01% max: 33.66% x̄: 3.36% x̃: 1.43%
95% mean confidence interval for cycles value: -1.60 5.43
95% mean confidence interval for cycles %-change: -0.03% 0.33%
Inconclusive result (value mean confidence interval includes 0).

LOST:   0
GAINED: 2

Iron Lake
total instructions in shared programs: 8137992 -> 8137874 (<.01%)
instructions in affected programs: 17501 -> 17383 (-0.67%)
helped: 104
HURT: 2
helped stats (abs) min: 1 max: 2 x̄: 1.17 x̃: 1
helped stats (rel) min: 0.25% max: 2.63% x̄: 0.87% x̃: 0.72%
HURT stats (abs)   min: 2 max: 2 x̄: 2.00 x̃: 2
HURT stats (rel)   min: 0.45% max: 0.45% x̄: 0.45% x̃: 0.45%
95% mean confidence interval for instructions value: -1.22 -1.00
95% mean confidence interval for instructions %-change: -0.94% -0.76%
Instructions are helped.

total cycles in shared programs: 188540038 -> 188539650 (<.01%)
cycles in affected programs: 704574 -> 704186 (-0.06%)
helped: 125
HURT: 84
helped stats (abs) min: 2 max: 96 x̄: 6.45 x̃: 4
helped stats (rel) min: <.01% max: 3.47% x̄: 0.42% x̃: 0.25%
HURT stats (abs)   min: 2 max: 58 x̄: 4.98 x̃: 4
HURT stats (rel)   min: 0.01% max: 2.75% x̄: 0.36% x̃: 0.33%
95% mean confidence interval for cycles value: -3.20 -0.52
95% mean confidence interval for cycles %-change: -0.19% -0.03%
Cycles are helped.

GM45
total instructions in shared programs: 5008889 -> 5008830 (<.01%)
instructions in affected programs: 8824 -> 8765 (-0.67%)
helped: 52
HURT: 1
helped stats (abs) min: 1 max: 2 x̄: 1.17 x̃: 1
helped stats (rel) min: 0.25% max: 2.38% x̄: 0.86% x̃: 0.72%
HURT stats (abs)   min: 2 max: 2 x̄: 2.00 x̃: 2
HURT stats (rel)   min: 0.45% max: 0.45% x̄: 0.45% x̃: 0.45%
95% mean confidence interval for instructions value: -1.27 -0.95
95% mean confidence interval for instructions %-change: -0.96% -0.71%
Instructions are helped.

total cycles in shared programs: 128969426 -> 128969128 (<.01%)
cycles in affected programs: 399798 -> 399500 (-0.07%)
helped: 74
HURT: 30
helped stats (abs) min: 2 max: 22 x̄: 6.76 x̃: 6
helped stats (rel) min: <.01% max: 1.83% x̄: 0.46% x̃: 0.29%
HURT stats (abs)   min: 2 max: 58 x̄: 6.73 x̃: 6
HURT stats (rel)   min: 0.06% max: 2.75% x̄: 0.42% x̃: 0.21%
95% mean confidence interval for cycles value: -4.60 -1.14
95% mean confidence interval for cycles %-change: -0.32% -0.08%
Cycles are helped.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>