test/ceph_crypto: do not read ceph.conf in global_init()

test/ceph_crypto: do not read ceph.conf in global_init()

ForkDeathTest.MD5 expect an empty output while global_init() complains
if ceph.conf is missing if 0 is passed in as the `flags`. this test
passes if ceph.conf is in current working directory, but jenkins does
not prepare this file for this test.

Fixes: http://tracker.ceph.com/issues/18128
Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit c72a2271a8012a66d7bbccf5766a73da5bb878d6)

Conflicts:
        src/test/ceph_crypto.cc - jewel does not have
             5af29540675b674c1985ff98b28a783ed124acf6