[pdb] Write TPI hash values to the TPI stream.

[pdb] Write TPI hash values to the TPI stream.

This completes being able to write all the interesting
values of a PDB TPI stream.

Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D24370

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281555 91177308-0d34-0410-b5e6-96231b3b80d8