[COFF, ARM64] Fix localaddress to handle stack realignment and variable size objects

[COFF, ARM64] Fix localaddress to handle stack realignment and variable size objects

Summary: This fixes using the correct stack registers for SEH when stack realignment is needed or when variable size objects are present.

Reviewers: rnk, efriedma, ssijaric, TomTan

Reviewed By: rnk, efriedma

Subscribers: javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D57183

llvm-svn: 352923