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

@@ -242,11 +242,11 @@
 print_sym(void *pointer)
 {
         int result;
         Dl_info sym_info;
 
-        uintptr_t end = NULL;
+        uintptr_t end = (uintptr_t)NULL;
 
         Sym *ext_info = NULL;
 
         result = dladdr1(pointer, &sym_info, (void **)&ext_info,
             RTLD_DL_SYMENT);