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>

arch/um/sys-i386/signal.c

@@ -458,11 +458,7 @@ long sys_sigreturn(struct pt_regs regs)
 		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 @@ long sys_rt_sigreturn(struct pt_regs regs)
 		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;

arch/um/sys-x86_64/signal.c

@@ -270,11 +270,7 @@ long sys_rt_sigreturn(struct pt_regs *regs)
 		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,
 			      &frame->fpstate))