Fix: libcib: cib__signon_query(): NULL-check correct pointer

cib_object is not NULL-checked until the very end. It should be checked
at the beginning to ensure we have a destination to store the CIB. Also
as a result, *cib_object is never NULL-checked. We need to check it at
the end to determine our return code.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>