[SDAG] Remove -enable-fmf-dag

This is no longer needed as spotted by Sanjay in
https://reviews.llvm.org/D31165.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298963 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed