restore: check that a restorer vma doesn't intersect with target vma-s

[ xemul: The fix effectively is -- stop scanning the 2nd vma list
         once we see, that the hint's end hits the next vma ]

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>