Port to Forte Developer 7 C compiler.

(struct YYLTYPE): If locations are not being used, declare a single
dummy member, as empty structs do not conform to the C standard.
(YYERROR, YYBACKUP): Do not use "do { ...; return foo; } while (0)";
the Forte Developer 7 C compiler complains that end-of-loop
code is not reached.

data/glr.c

@@ -197,6 +197,8 @@ typedef struct YYLTYPE
   int first_column;
   int last_line;
   int last_column;
+],[
+  char yydummy;
 ])[
 } YYLTYPE;
 # define YYLTYPE_IS_DECLARED 1
@@ -682,7 +684,7 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
 # undef YYABORT
 # define YYABORT return yyabort
 # undef YYERROR
-# define YYERROR do { yystack->yyerrState = 0; return yyerr; } while (0)
+# define YYERROR return yyerrok, yyerr
 # undef YYRECOVERING
 # define YYRECOVERING (yystack->yyerrState != 0)
 # undef yyclearin
@@ -691,10 +693,8 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
 # define YYFILL(N) yyfill (yyvsp, &yylow, N, yynormal)
 # undef YYBACKUP
 # define YYBACKUP(Token, Value)						     \
-  do {									     \
-    yyerror (]b4_yyerror_args["syntax error: cannot back up");		     \
-    YYERROR;								     \
-  } while (0)
+  return yyerror (]b4_yyerror_args["syntax error: cannot back up"),	     \
+	 yyerrok, yyerr
 
   yylow = 1;
   if (yyrhslen == 0)
@@ -2016,6 +2016,8 @@ b4_location_if([
   int first_column;
   int last_line;
   int last_column;
+],[
+  char yydummy;
 ])
 } YYLTYPE;
 # define YYLTYPE_IS_DECLARED 1