native_usergs_sysret64 is described as

	extern void native_usergs_sysret64(void)

so lets add ENDPROC here
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: heukelum@fastmail.fm
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>