Refactor some more PDB reading code into DebugInfoPDB.

Differential Revision: http://reviews.llvm.org/D19445
Reviewed By: David Majnemer

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267564 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed