arm: switch to generic old sigaction()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/arm/include/asm/signal.h

@@ -16,13 +16,6 @@ typedef struct {
 	unsigned long sig[_NSIG_WORDS];
 } sigset_t;
 
-struct old_sigaction {
-	__sighandler_t sa_handler;
-	old_sigset_t sa_mask;
-	unsigned long sa_flags;
-	__sigrestore_t sa_restorer;
-};
-
 #define __ARCH_HAS_SA_RESTORER
 
 #include <asm/sigcontext.h>