new helper: sigmask_to_save()

replace boilerplate "should we use ->saved_sigmask or ->blocked?"
with calls of obvious inlined helper...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/sched.h

@@ -2213,6 +2213,14 @@ static inline void restore_saved_sigmask(void)
 		set_current_blocked(&current->saved_sigmask);
 }
 
+static inline sigset_t *sigmask_to_save(void)
+{
+	sigset_t *res = &current->blocked;
+	if (unlikely(test_restore_sigmask()))
+		res = &current->saved_sigmask;
+	return res;
+}
+
 static inline int kill_cad_pid(int sig, int priv)
 {
 	return kill_pid(cad_pid, sig, priv);