Revision 665201

Thrift: docstring revamp step 2.

Summary:
It was a bad idea to let doxygen comments become a part of the parse tree.
We now get them a totally different way.  The lexer stashes the docsting
contents in a global, and the parser actions (not the rules) pull it out.
This should prevent doxygen comments from ever causing parse errors.

Blame Rev: 52678, 52732

Reviewed By: mcslee

Test Plan:
Recompiled thrift.
Thrifted a bunch of files and saw no parse errors (or C++ compile errors).
Thrifted DocTest.thrift with dump_docs on.

Revert Plan: ok