um: switch {rt_,}sigreturn() to set_current_blocked()

same story as on x86 native...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c
index 89a4662..4403b48 100644
--- a/arch/um/sys-i386/signal.c
+++ b/arch/um/sys-i386/signal.c
@@ -458,11 +458,7 @@
 		goto segfault;
 
 	sigdelsetmask(&set, ~_BLOCKABLE);
-
-	spin_lock_irq(&current->sighand->siglock);
-	current->blocked = set;
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
+	set_current_blocked(&set);
 
 	if (copy_sc_from_user(&current->thread.regs, sc))
 		goto segfault;
@@ -489,11 +485,7 @@
 		goto segfault;
 
 	sigdelsetmask(&set, ~_BLOCKABLE);
-
-	spin_lock_irq(&current->sighand->siglock);
-	current->blocked = set;
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
+	set_current_blocked(&set);
 
 	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 		goto segfault;