This implements the legacy passes in terms of the new ones. It adds
basic testing using explicit runs of the passes. Next up will be wiring
the basic output mechanism of opt up when the new pass manager is
engaged unless bitcode writing is requested.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199049 91177308-0d34-0410-b5e6-96231b3b80d8
