* data/c.m4 (b4_copyright, b4_epilogue, b4_location_initial_column,
b4_location_initial_line, p4_parse_param, b4_ints_in, b4_flag_if,
b4_define_flag_if and uses, b4_basename, b4_syncline, b4_user_code,
b4_define_user_cde and uses): Remove.
(b4_comment, b4_prefix, b4_sync_start): New.
* data/bison.m4: New file, with most of the content removed from c.m4.
* src/muscle_tab.h: Use "do {...} while(0)" throughout.
* src/output.c (output_skeleton): Pass bison.m4.
(prepare): Pass glr_flag and nondeterministic_flag. Pass prefix
only if specified.
