Fix some display bugs in llvm-pdbdump.

We were incorrectly reporting all non-64 bit integers as int64s.
This is most evident when trying to print the "short" type, but
in theory could happen with chars too (although usually chars use
a different builtin type).

Additionally, we were using the wrong check when deciding whether
to print an enum definition as a global enum.  We were checking
whether or not the enum was "nested", and if so saving it until
we print the class definition that it was nested in.  But this is
not correct in rare situations where the enum is nested, but the
class that it's nested in does not have type information in the PDB.
So instead we check if there is a class definition for the parent
in the PDB.  If so we save it for later, otherwise we print it.

llvm-svn: 265993