powerpc: switch to generic sigaltstack

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/powerpc/kernel/ppc32.h b/arch/powerpc/kernel/ppc32.h
index 02fb0ee..f6bee3e 100644
--- a/arch/powerpc/kernel/ppc32.h
+++ b/arch/powerpc/kernel/ppc32.h
@@ -34,12 +34,6 @@
        compat_sigset_t sa_mask;		/* A 32 bit mask */
 };
 
-typedef struct sigaltstack_32 {
-	unsigned int ss_sp;
-	int ss_flags;
-	compat_size_t ss_size;
-} stack_32_t;
-
 struct pt_regs32 {
 	unsigned int gpr[32];
 	unsigned int nip;
@@ -75,7 +69,7 @@
 struct ucontext32 { 
 	unsigned int	  	uc_flags;
 	unsigned int 	  	uc_link;
-	stack_32_t	 	uc_stack;
+	compat_stack_t	 	uc_stack;
 	int		 	uc_pad[7];
 	compat_uptr_t		uc_regs;	/* points to uc_mcontext field */
 	compat_sigset_t	 	uc_sigmask;	/* mask last for extensibility */