For associating token numbers with token names for "yacc.c", don't use

#define statements unless `--yacc' is specified; always use enum
yytokentype.  Most important discussions start at:
<http://lists.gnu.org/archive/html/bison-patches/2005-09/msg00053.html>,
<http://lists.gnu.org/archive/html/bison-patches/2005-12/msg00052.html>,
and
<http://lists.gnu.org/archive/html/bison-patches/2006-06/msg00043.html>.
* NEWS (2.3+): Mention.
* data/c.m4 (b4_yacc_if): New.
(b4_token_enums_defines): Use b4_yacc_if to decide whether to add the
token #define's.
* doc/bison.texinfo (Bison Options): Describe the effect of `--yacc'
on token name definitions.
* src/getargs.c (usage): Capitalize `Yacc' in English.
* src/output.c (prepare): Define b4_yacc_flag.
* tests/regression.at (Early token definitions): Test that tokens names
are defined before the pre-prologue not just before the post-prologue.
Remove this test case and copy to...
(Early token definitions with --yacc): ... this to test #define's.
(Early token definitions without --yacc): ... and this to test enums.

src/getargs.c

@@ -217,7 +217,7 @@ Operation modes:\n\
   -h, --help                 display this help and exit\n\
   -V, --version              output version information and exit\n\
       --print-localedir      output directory containing locale-dependent data\n\
-  -y, --yacc                 emulate POSIX yacc\n"), stdout);
+  -y, --yacc                 emulate POSIX Yacc\n"), stdout);
       putc ('\n', stdout);
 
       fputs (_("\

src/output.c

@@ -590,6 +590,7 @@ prepare (void)
   MUSCLE_INSERT_BOOL ("locations_flag", locations_flag);
   MUSCLE_INSERT_BOOL ("pure_flag", pure_parser);
   MUSCLE_INSERT_BOOL ("synclines_flag", !no_lines_flag);
+  MUSCLE_INSERT_BOOL ("yacc_flag", yacc_flag);
 
   /* File names.  */
   MUSCLE_INSERT_STRING ("prefix", spec_name_prefix ? spec_name_prefix : "yy");