Add an "alignment" field to the MachineFunction object. It makes more sense to

Add an "alignment" field to the MachineFunction object. It makes more sense to
have the alignment be calculated up front, and have the back-ends obey whatever
alignment is decided upon.

This allows for future work that would allow for precise no-op placement and the
like.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74564 91177308-0d34-0410-b5e6-96231b3b80d8