gst/: Make those function act on the ghostpad target when it's a ghostpad. (Closes...

gst/: Make those function act on the ghostpad target when it's a ghostpad. (Closes #331727)

Original commit message from CVS:

* gst/gstpad.c: (gst_pad_set_blocked_async):
* 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): Make those function act on the
ghostpad target when it's a ghostpad. (Closes #331727)
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