[PDB] Add support for dumping Typedef records.

These work a little differently because they are actually in
the globals stream and are treated as symbol records, even though
DIA presents them as types.  So this also adds the necessary
infrastructure to cache records that live somewhere other than
the TPI stream as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343507 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed