[InstrTypes] add frem and fneg with FMF creators

The more popular opcodes were added at r325730, but we
should have everything here for symmetry. I think both
of these can be used in InstCombine already, but I'll
make those changes as separate clean-ups for InstCombine.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325832 91177308-0d34-0410-b5e6-96231b3b80d8