Suppress a "clobbered" warning

process.c

@@ -3537,9 +3537,7 @@ rb_exec_atfork(void* arg, char *errmsg, size_t errmsg_buflen)
 {
     return rb_exec_async_signal_safe(arg, errmsg, errmsg_buflen); /* hopefully async-signal-safe */
 }
-#endif
 
-#ifdef HAVE_WORKING_FORK
 #if SIZEOF_INT == SIZEOF_LONG
 #define proc_syswait (VALUE (*)(VALUE))rb_syswait
 #else
@@ -3928,7 +3926,7 @@ retry_fork_async_signal_safe(int *status, int *ep,
     volatile int try_gc = 1;
     struct child_handler_disabler_state old;
     int err;
-    rb_nativethread_lock_t *const waitpid_lock_init =
+    rb_nativethread_lock_t *const volatile waitpid_lock_init =
         (w && WAITPID_USE_SIGCHLD) ? &GET_VM()->waitpid_lock : 0;
 
     while (1) {