kernel: add lockdep expression

Lockdep is the kernel's locking validation/debugging tool and has seen
heavy pro-active usage and development. In Linux 3.14, it's now
available directly to userspace for the same purpose. It comes with a
convenient utility to LD_PRELOAD a shared library for validation, or a
user-space API to link to directly.

Signed-off-by: Austin Seipp <aseipp@pobox.com>