Revert "Workaround for linking error w/ clang & glibc 2.31+"

[BrettDong]

Summary

None

Purpose of change

This removes the workaround to linking error when compiling with LLVM/Clang on a system with glibc version 2.31 or newer (#47099). The linking error only occurs when -ffast-math is used, but the flag was removed in 71c718a in #50390, so this workaround is no longer needed.

Describe the solution

Revert #47099.

Describe alternatives you've considered

Testing

Additional context

[akrieger]

I'm curious if we ever measured how much -ffast-math improved performance / removing it dropped performance. -fno-builtin probably has some nontrivial cost associated with it also, so maybe it balances out :)

[kevingranade]

It basically doesn't matter because we ran into --fast-math actually causing incorrect behavior, it seemed worth doing because it was "free", but I didn't anticipate the kind of failure modes it could trigger.
Hypothetically we could enable some of the sub-options that --fast-math bundles, but I don't anticipate it being meaningful, we mostly just eschew floating point operations.

[anothersimulacrum]

IIRC, @jbytheway talked about it causing a slowdown in lighting that #44558 would likely be the solution to.

[kevingranade]

Yea I need to get back on that, it was really promising.