Repair longstanding damage introduced by the AST merge:
Repair longstanding damage introduced by the AST merge:

- Get rid of pgen.c and tokenizer_pgen.c.

- Include tokenizer.c.

All the -uall tests pass on my WinXP VC7.1 box now.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator