[libspirv] Fix unordered GreaterThan*/LessThan* relational built-ins (#22104)
The old implementations was using ordered comparison. This PR fixes them
to use unordered comparison which is required for NaN handling.
- FUnordGreaterThan: ogt -> ugt
- FUnordGreaterThanEqual: oge -> uge
- FUnordLessThan: olt -> ult
- FUnordLessThanEqual: ole -> ule
Example llvm-diff change (> is reference):
in function _Z25__spirv_FUnordGreaterThanff:
> %3 = fcmp contract ogt float %0, %1
< %3 = fcmp contract ugt float %0, %1