Dumping a symbol often requires access to data that isn't inside
the symbol hierarchy, but which is only accessible through the
top-level session. This patch is a pure interface change to give
symbols a reference to the session.
llvm-svn: 228542
This patch implements a few of the optional suggestions from the
initial patch comitting libpdb. In particular, it implements a
virtual function out of line for each of the concrete classes.
A few other minor cleanups exist as well, such as using override
instead of virtual, etc.
llvm-svn: 228516