5218 posix definition of NULL
correct unistd.h and iso/stddef_iso.h
update gate source affected

@@ -266,8 +266,8 @@
 
 void
 pt_sugg_as_root(void)
 {
         pt_sugg_add("Suggestion: run as root to get suggestions"
-            " for reducing system power consumption",  40, NULL, NULL,
+            " for reducing system power consumption",  40, '\0', NULL,
             NULL);
 }