assert: allow assertions inside calls to dout()
assert: allow assertions inside calls to dout()

We should handle the situation where we assert() while already holding
the dout() lock. At the same time, we want to get the dout lock if we
can, because it makes the logs look nicer. pthread_mutex_trylock solves
the dilemma.

Signed-off-by: Colin McCabe <7b35906f1d014e74a9dc8c913eb229119df647aa@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph