Simplify the i18n of the error messages.

* data/lalr1.cc: Comment changes.
	* data/yacc.c (yysyntax_error): Rewrite, using a switch as in
	lalr1.cc instead of building dynamically the format string.

data/lalr1.cc

@@ -1393,7 +1393,8 @@ b4_error_verbose_if([int yystate, int yytoken],
 	int yychecklim = yylast_ - yyn + 1;
 	int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
 
-        // Number of "expected" tokens.
+        // Number of reported tokens (one for the "unexpected", one per
+        // "expected").
 	size_t yycount = 0;
         // Its maximum.
         enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };