[dwarfdump] Add DWARF verifiers for address ranges

This patch started as an attempt to rebase Greg's differential (D32821).
The result is both quite similar and different at the same time. It adds
the following checks:

 - Verify that all address ranges in a DIE are valid.
 - Verify that no ranges within the DIE overlap.
 - Verify that no ranges overlap with the ranges of a sibling.
 - Verify that children are completely contained in its (direct)
   parent's address range. (unless both are subprograms)

Differential revision: https://reviews.llvm.org/D37696

llvm-svn: 313255