The location tracking mechanism is precious for parse error

messages.  Nevertheless, it is enabled only when `@n' is used in
the grammar, which is a different issue (you can use it in error
message, but not in the grammar per se).  Therefore, there should
be another means to enable it.
* src/getargs.c (getargs): Support `--locations'.
(usage): Report it.
* src/getargs.h (locationsflag): Export it.
* src/lex.c (percent_table): Support `%locations'.
* src/reader.c (yylsp_needed): Remove this variable, now replaced
with `locationsflag'.
* doc/bison.texinfo: Document `--locations' and `%locations'.
Sort the options.
* tests/calc.m4: Test it.
For regularity of the names, replace each
(nolineflag, toknumflag, rawtokenumflag, noparserflag): with...
(no_lineflag, token_tableflag, rawflag, no_parserflag): this.
In addition replace each `flag' with `_flag'.

src/print.c

@@ -351,10 +351,10 @@ print_results (void)
   if (any_conflicts)
     print_conflicts ();
 
-  if (verboseflag)
+  if (verbose_flag)
     print_grammar ();
 
-  if (verboseflag)
+  if (verbose_flag)
     for (i = 0; i < nstates; i++)
       print_state (i);
 }