stage2 sema: Implement comptime result for comparison of uint to comptime value

This adds a comptime result when comparing a comptime value to an
unsigned integer. For example:
   ( 0 <= (unsigned runtime value)) => true
   (-1 <  (unsigned runtime value)) => true
   ((unsigned runtime value) < -15) => false
a7a508fcd9Cody Tapscott committed on 2/27/2022, 9:24:28 AMparentb529484
2 files changedLine totals unavailable