missing_threads.h: threads.h exists since glibc-2.28

src/basic/memory-util.c

@@ -1,9 +1,9 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <threads.h>
 #include <unistd.h>
 
 #include "memory-util.h"
-#include "missing_threads.h"
 
 size_t page_size(void) {
         static thread_local size_t pgsz = 0;