consolidate kernel-side struct sigaction declarations

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

arch/ia64/include/asm/signal.h

@@ -26,12 +26,6 @@ typedef struct {
 	unsigned long sig[_NSIG_WORDS];
 } sigset_t;
 
-struct sigaction {
-	__sighandler_t sa_handler;
-	unsigned long sa_flags;
-	sigset_t sa_mask;		/* mask last for extensibility */
-};
-
 #  include <asm/sigcontext.h>
 
 # endif /* !__ASSEMBLY__ */

arch/ia64/include/asm/unistd.h

@@ -47,7 +47,6 @@ asmlinkage unsigned long sys_mmap2(
 				int prot, int flags,
 				int fd, long pgoff);
 struct pt_regs;
-struct sigaction;
 asmlinkage long sys_ia64_pipe(void);
 
 /*