GlobalISel/IRTranslator resetTargetOptions based on function attributes

Update TargetMachine.Options with function attributes before we start
to generate MIR instructions. This allows access to correct function
attributes via TargetMachine.Options (it used to access attributes of
the function that was translated first).
This affects some existing tests with "no-nans-fp-math" attribute.
Follow-up on D87456.

Differential Revision: https://reviews.llvm.org/D87511