[IA64] wire up sendmmsg() syscall for Itanium

Add entries in unistd.h and entry.S to make this new syscall visible.

Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index 9ca8019..97dd2ab 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -1776,6 +1776,7 @@
 	data8 sys_clock_adjtime
 	data8 sys_syncfs
 	data8 sys_setns				// 1330
+	data8 sys_sendmmsg
 
 	.org sys_call_table + 8*NR_syscalls	// guard against failures to increase NR_syscalls
 #endif /* __IA64_ASM_PARAVIRTUALIZED_NATIVE */