[PDB] Add a test that verifies every known type record.

We had a lot of one-off tests for this type and that type,
or "every type that happens to be generated by this program
I built".  Eventually I got a bug report filed where we were
crashing on a type that was not covered by any of these tests.
So this test carefully constructs a minimal C++ program that
will cause every type we support to be emitted.  This ensures
full coverage for type records.

Differential Revision: https://reviews.llvm.org/D34915

llvm-svn: 307187