To debug a deadlock, we really want to know what lock is actually
locked, so we can figure out what is using that lock. This PR
adds support for this, using trylock to check if every lock on
the system is free or in use. Will really need to be run a few
times in quick succession to verify that it's not a transient
lock and it's actually stuck, but that's not really a big deal.
Signed-off-by: Matt Heon <mheon@redhat.com>