This lets PDB readers lookup type record data by type index in O(log n)
time. It also enables makes cvdump -t work on PDBs produced by LLD.
cvdump will not dump a PDB that doesn't have an index-to-offset table.
The table is sorted by type index, and has an entry every 8KB. Looking
up a type record by index is a binary search of this table, followed by
a scan of at most 8KB.
What actually happened with this test is that @ruiu removed the llvm-pdbdump raw FileCheck line in rL291739, and these RAW checks became stale. They were essentially a "golden output" style test that looks at the complete PDB output before I touched it, and that's where all the diffs other than the TypeIndexOffsets diff come from.
I've re-added the RUN line and regenerated the output in this change because I want to look for the TypeIndexOffset goo at the end of the type stream.
Here's what I'm going to do: I'll land this change and update the RAW checks and we can figure out what we want to do about them separately. This change will just add the TypeIndexOffset checks.