gst/gstbin.c: (de)activate src pads before calling state_change on the childs.

gst/gstbin.c: (de)activate src pads before calling state_change on the childs.

Original commit message from CVS:
* gst/gstbin.c: (activate_pads),
(iterator_activate_fold_with_resync), (gst_bin_src_pads_activate),
(gst_bin_change_state_func):
(de)activate src pads before calling state_change on the childs.
This is to avoid the case where a src ghostpad is blocked (holding the
stream lock), which would block the deactivation of the ghostpad's
target pad.
* gst/gstghostpad.c: (gst_proxy_pad_do_query_type),
(gst_proxy_pad_do_event), (gst_proxy_pad_do_query),
(gst_proxy_pad_do_internal_link), (gst_proxy_pad_do_bufferalloc),
(gst_proxy_pad_do_chain), (gst_proxy_pad_do_getrange),
(gst_proxy_pad_do_checkgetrange), (gst_proxy_pad_do_getcaps),
(gst_proxy_pad_do_acceptcaps), (gst_proxy_pad_do_fixatecaps),
(gst_proxy_pad_do_setcaps), (gst_proxy_pad_set_target_unlocked),
(gst_proxy_pad_set_target), (gst_proxy_pad_get_internal),
(gst_proxy_pad_dispose), (gst_proxy_pad_init),
(gst_ghost_pad_parent_set), (gst_ghost_pad_parent_unset),
(gst_ghost_pad_class_init),
(gst_ghost_pad_internal_do_activate_push),
(gst_ghost_pad_internal_do_activate_pull),
(gst_ghost_pad_do_activate_push), (gst_ghost_pad_do_activate_pull),
(gst_ghost_pad_do_link), (gst_ghost_pad_do_unlink),
(gst_ghost_pad_dispose), (gst_ghost_pad_new_no_target),
(gst_ghost_pad_new), (gst_ghost_pad_set_target):
GhostPads now create their internal GstProxyPad at creation (and not
when they're linked, as it was being done previously).
The internal and target pads are linked straight away.
The data will also travel through the other pad in order to make
pad blocking and probes non-hackish (the probe/block now really happens
on the GhostPad and not on the target).
* gst/gstpad.c: (gst_pad_set_blocked_async),
(gst_pad_link_prepare), (gst_pad_push_event):
Remove previous ghostpad cruft.
* gst/gstutils.c: (gst_pad_add_data_probe),
(gst_pad_add_event_probe), (gst_pad_add_buffer_probe),
(gst_pad_remove_data_probe), (gst_pad_remove_event_probe),
(gst_pad_remove_buffer_probe):
Remove previous ghost pad cruft.
Added more detailed debug statements.
* tests/check/gst/gstghostpad.c: (GST_START_TEST):
Fix the testsuite for refcounting changes.
The comments about who has references were correct, but the refcount
being checked wasn't the same (!?!).