[IA64] silence GCC ia64 unused variable warnings

Tell GCC to stop spewing out unnecessary warnings for unused variables
passed to functions as pointers for ia64 files.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/process.c

@@ -513,7 +513,8 @@ copy_thread (int nr, unsigned long clone_flags,
 static void
 do_copy_task_regs (struct task_struct *task, struct unw_frame_info *info, void *arg)
 {
-	unsigned long mask, sp, nat_bits = 0, ip, ar_rnat, urbs_end, cfm;
+	unsigned long mask, sp, nat_bits = 0, ar_rnat, urbs_end, cfm;
+	unsigned long uninitialized_var(ip);	/* GCC be quiet */
 	elf_greg_t *dst = arg;
 	struct pt_regs *pt;
 	char nat;