Fix a few portability issues, adjust error messages.

contrib/tsearch2/snowball/api.c

+#include <stdlib.h>
 
 #include "header.h"
 

contrib/tsearch2/snowball/english_stem.c

@@ -373,7 +373,6 @@ static int r_prelude(struct SN_env * z) {
             z->c = c;
             break;
         }
-    lab1:
         z->c = c;
     }
     return 1;

contrib/tsearch2/snowball/header.h

-
-#include <limits.h>
-
 #include "api.h"
 
-#define MAXINT INT_MAX
-#define MININT INT_MIN
-
 #define HEAD 2*sizeof(int)
 
 #define SIZE(p)        ((int *)(p))[-1]