Use pointers to the MCAsmInfo and MCRegInfo.

Someone may want to do something crazy, like replace these objects if they
change or something.

No functionality change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184175 91177308-0d34-0410-b5e6-96231b3b80d8
Hopefully fix the MSVS build after r184105

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184178 91177308-0d34-0410-b5e6-96231b3b80d8