proc_parse: handle errors for breadline()

00:03:27.746 (00.008815) Error (bfd.c:149): bfd: Error reading file: No such process

Reported-by: Mr Jenkins
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>