cmpxchg8b fix - added cmpxchg16b

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4522 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/target-i386/helper.h b/target-i386/helper.h
index 9df198a..9bbf4fc 100644
--- a/target-i386/helper.h
+++ b/target-i386/helper.h
@@ -75,6 +75,9 @@
 void helper_rsm(void);
 void helper_into(int next_eip_addend);
 void helper_cmpxchg8b(target_ulong a0);
+#ifdef TARGET_X86_64
+void helper_cmpxchg16b(target_ulong a0);
+#endif
 void helper_single_step(void);
 void helper_cpuid(void);
 void helper_rdtsc(void);