locks: Add leases c/r for kernels v4.0 and older

Information about locks in /proc/<pid>/fdinfo is presented only since
kernel v4.1. This patch adds logic to *note_file_lock* to match leases
and OFDs.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>