check/gst/gstminiobject.c: don't use check calls from threads; check probably isn't threadsafe and using a lock to ma...

Original commit message from CVS:

* check/gst/gstminiobject.c: (thread_ref), (GST_START_TEST),
(gst_mini_object_suite):
don't use check calls from threads; check probably isn't
threadsafe and using a lock to make it threadsafe would
defeat the purpose of this check
* gst/check/gstcheck.c:
* gst/check/gstcheck.h:
use GST_DEBUG some more