Split DescribeAddressIfStack between a function that gets all the information,...

Split DescribeAddressIfStack between a function that gets all the information, and one that prints it.

Summary:
Replacement for part of D23518
This deals with stack addresses.

Reviewers: kcc, samsonov

Subscribers: kubabrecka, llvm-commits

Differential Revision: https://reviews.llvm.org/D23605

llvm-svn: 278958