consolidate declarations of k_sigaction

Only alpha and sparc are unusual - they have ka_restorer in it.
And nobody needs that exposed to userland.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/signal.h b/include/linux/signal.h
index ed1e71f..01451a1 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -249,6 +249,13 @@
 extern int show_unhandled_signals;
 extern int sigsuspend(sigset_t *);
 
+struct k_sigaction {
+	struct sigaction sa;
+#ifdef __ARCH_HAS_KA_RESTORER
+	__sigrestore_t ka_restorer;
+#endif
+};
+
 extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
 extern void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka, struct pt_regs *regs, int stepping);
 extern void exit_signals(struct task_struct *tsk);