Fix math-errno issue (#66381)

Update handling of math errno. This change updates the logic for
generation of math intrinics in place of math library function calls.
The previous logic https://reviews.llvm.org/D151834 was incorrectly
using intrinsics when math errno handling was needed at optimization
levels above -O0.
This also fixes issue mentioned in https://reviews.llvm.org/D151834 by
@uabelho
This is joint work with @andykaylor Andy.