Still making progress in separating Bison into (i) input, (ii)

Still making progress in separating Bison into (i) input, (ii)
process, (iii) output: now we can directly output the parser file
without using table_obstack at all.
* src/files.c, src/files.h (table_obstack): Bye bye.
(parser_file_name): New.
* src/files.c (compute_output_file_names): Compute it.
* src/output.c (actions_output, output_parser)
(output_master_parser): To a file instead of an obstack.