* data/bison.m4 (b4_user_requires, b4_user_provides): New.
(b4_user_start_header): Remove.
* data/glr.c: Use new macros instead of b4_*start_header
* data/bison.m4 (b4_user_requires, b4_user_provides): New.
(b4_user_start_header): Remove.
* data/glr.c: Use new macros instead of b4_*start_header