* src/reader.h, src/reader.c (gram_error): ... can't get

yycontrol without making too strong assumptions on the parser
itself.
* src/output.c (prepare_tokens): Use the real 0th value of
token_translations instead of `0'.
* src/parse-gram.y (yyerror): Don't rely on yycontrol being
visible here.
* data/yacc.c (yyreport_parse_error): Rename yylocation as yylloc
for the time being: %locations ought to provide it to yyerror.

data/yacc.c

@@ -650,7 +650,7 @@ b4_c_function([yyreport_parse_error],
 	      [[int],     [yystate]],
 	      [[int],     [yychar]],
 	      [[YYSTYPE], [yyvalue]]b4_location_if([,
-	      [[YYLTYPE], [yylocation]]]))
+	      [[YYLTYPE], [yylloc]]]))
 [{
 #if YYERROR_VERBOSE
   int yyn = yypact[yystate];
@@ -705,7 +705,7 @@ b4_c_function([yyreport_parse_error],
   (void) yystate;
   (void) yychar;
   (void) yyvalue;
-  ]b4_location_if([(void) yylocation;])[
+  ]b4_location_if([(void) yylloc;])[
 }]