syscalls: Add sys_madvise

Will need it for VMA restore.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/syscall-x86-64.def

@@ -22,6 +22,7 @@ __NR_rt_sigprocmask	14		sys_sigprocmask		(int how, k_rtsigset_t *set, k_rtsigset
 __NR_rt_sigreturn	15		sys_rt_sigreturn	(void)
 __NR_ioctl		16		sys_ioctl		(unsigned int fd, unsigned int cmd, unsigned long arg)
 __NR_mincore		27		sys_mincore		(void *addr, unsigned long size, unsigned char *vec)
+__NR_madvise		28		sys_madvise		(unsigned long start, size_t len, int behavior)
 __NR_shmat		30		sys_shmat		(int shmid, void *shmaddr, int shmflag)
 __NR_pause		34		sys_pause		(void)
 __NR_nanosleep		35		sys_nanosleep		(struct timespec *req, struct timespec *rem)