Revert "[MergeICmps] Disable mergeicmps if the target does not want to handle memcmp expansion."

Still a few stability issues on windows.

This reverts commit 67e3db9bc121ba244e20337aabc7cf341a62b545.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315058 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed