x86: signal: split out frame setups

Make setup_rt_frame() and split out frame setups from handle_signal().
This is for cosmetic unification of handle_signal().

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --cc arch/x86/kernel/signal_32.c
Simple merge

diff --cc arch/x86/kernel/signal_64.c
Simple merge