[codeview] Fix handling of S_HEAPALLOCSITE

The type index is from the TPI stream, not the IPI stream. Fix the
dumper, fix type index discovery, and add a test in LLD.

Also improve the log message we emit when we fail to rewrite type
indices in LLD. That's how I found this bug.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316461 91177308-0d34-0410-b5e6-96231b3b80d8