Fix a few minor issues when dumping symbols.

1) We weren't handling symbol types that weren't able to parse,
   even if we knew what the leaf type was.  This was triggering
   when trying to dump /DEBUG:FASTLINK PDBs, where we expect a
   certain symbol to show up, but we just don't know how to parse
   it.
2) We lost the code for dumping record bytes, so this was added
   back.

llvm-svn: 311116