[PM] Port MemCpyOpt to the new PM.

[PM] Port MemCpyOpt to the new PM.

The need for all these Lookup* functions is just because of calls to
getAnalysis inside methods (i.e. not at the top level) of the
runOnFunction method. They should be straightforward to clean up when
the old PM is gone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272615 91177308-0d34-0410-b5e6-96231b3b80d8