sparc: Prevent no-handler signal syscall restart recursion.

Explicitly clear the "in-syscall" bit when we have no signal
handler and back up the program counters to back up the system
call.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc arch/sparc/kernel/signal32.c
Simple merge

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

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