--- configure.orig	2021-03-04 14:19:15.000000000 +1100
+++ configure	2021-03-04 14:27:17.000000000 +1100
@@ -10127,13 +10127,13 @@
       void *foo(void *parm) {
         return NULL;
       }
-      main() {
+      int main() {
         pthread_attr_t attr;
         pthread_t id;
-        if (pthread_attr_init(&attr)) exit(-1);
-        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) exit(-1);
-        if (pthread_create(&id, &attr, foo, NULL)) exit(-1);
-        exit(0);
+        if (pthread_attr_init(&attr)) return (-1);
+        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) return (-1);
+        if (pthread_create(&id, &attr, foo, NULL)) return (-1);
+        return (0);
       }
 _ACEOF
 if ac_fn_c_try_run "$LINENO"; then :
@@ -13604,7 +13604,7 @@
   int main()
   {
 	/* Success: exit code 0 */
-        exit((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
+        return ((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
   }
 
 _ACEOF
@@ -13941,7 +13941,7 @@
 
 int main()
 {
-	exit(((-1)>>3 == -1) ? 0 : 1);
+	return (((-1)>>3 == -1) ? 0 : 1);
 }
 
 _ACEOF
@@ -14412,6 +14412,9 @@
 /* end confdefs.h.  */
 
 #include <poll.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 
 int main()
 {