3.13.0-77.121) is not available, but a newer one is (3.13.0-166.216). We redirected you there.
/usr/lib/linux-tools/3.19.0-51-lowlatency/usbip is in linux-tools-3.19.0-51-lowlatency 3.19.0-51.58~14.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/3.19.0-51-lowlatency/../../linux-lts-vivid-tools-3.19.0-51/usbip