[NFC] Change MemIntrinsicInst::setAlignment() to take an unsigned instead of a Constant

Summary:
 In preparation for https://reviews.llvm.org/D41675 this NFC changes this
prototype of MemIntrinsicInst::setAlignment() to accept an unsigned instead
of a Constant.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@322403 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed