push fast-math check for machine-combiner reassociations into instruction-type check; NFC

This makes it simpler to add instruction types that don't depend on fast-math.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243596 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed