unify SS_ONSTACK/SS_DISABLE definitions

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

arch/alpha/include/asm/signal.h

@@ -98,12 +98,6 @@ typedef unsigned long sigset_t;
 #define SA_ONESHOT	SA_RESETHAND
 #define SA_NOMASK	SA_NODEFER
 
-/* 
- * sigaltstack controls
- */
-#define SS_ONSTACK	1
-#define SS_DISABLE	2
-
 #define MINSIGSTKSZ	4096
 #define SIGSTKSZ	16384