AllocaInst should store Align instead of MaybeAlign.

Along the lines of D77454 and D79968.  Unlike loads and stores, the
default alignment is getPrefTypeAlign, to match the existing handling in
various places, including SelectionDAG and InstCombine.

Differential Revision: https://reviews.llvm.org/D80044

GitOrigin-RevId: 4f04db4b5439f390c48408f9b94875810e88ffc6
2 files changed