tests/check/elements/: Don't use gst_element_get_pad(), it's a bad, bad method.

tests/check/elements/: Don't use gst_element_get_pad(), it's a bad, bad method.

Original commit message from CVS:
* tests/check/elements/avimux.c: (setup_src_pad),
(teardown_src_pad):
* tests/check/elements/icydemux.c: (icydemux_found_pad),
(GST_START_TEST):
* tests/check/elements/matroskamux.c: (setup_src_pad),
(teardown_src_pad), (setup_sink_pad), (teardown_sink_pad):
* tests/check/elements/videocrop.c: (video_crop_get_test_caps),
(GST_START_TEST):
* tests/check/elements/wavpackparse.c: (wavpackparse_found_pad),
(setup_wavpackparse), (cleanup_wavpackparse):
Don't use gst_element_get_pad(), it's a bad, bad method.