osd/dmclock/testing: reorganize testing, building now optional
Modify cmake files to take advantage or re-organization of dmclock's
cmake set-up, specifically not having dmclock's cmake files call
add_test. Remove dmclock tests from being dependencies on ceph's
"test" target. Make change so dmclock tests are not built unless
WITH_TESTS and WITH_DMCLOCK_TESTS are both set. This is so openSUSE
Leap will build correctly.
Signed-off-by: J. Eric Ivancich <ivancich@redhat.com>