new helper: signal_delivered()

Does block_sigmask() + tracehook_signal_handler();  called when
sigframe has been successfully built.  All architectures converted
to it; block_sigmask() itself is gone now (merged into this one).

I'm still not too happy with the signature, but that's a separate
story (IMO we need a structure that would contain signal number +
siginfo + k_sigaction, so that get_signal_to_deliver() would fill one,
signal_delivered(), handle_signal() and probably setup...frame() -
take one).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index c126eba..fd2392a 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -557,12 +557,7 @@
 		force_sigsegv(sig, tsk);
 		return;
 	}
-
-	/*
-	 * Block the signal if we were successful.
-	 */
-	block_sigmask(ka, sig);
-	tracehook_signal_handler(sig, info, ka, regs, 0);
+	signal_delivered(sig, info, ka, regs, 0);
 }
 
 /*