[LAA] Re-check bit-width of pointers after stripping.

Summary:
- As the pointer stripping now tracks through `addrspacecast`, prepare
  to handle the bit-width difference from the result pointer.

Reviewers: jdoerfert

Subscribers: jvesely, nhaehnle, hiraditya, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64928

llvm-svn: 366470