tests/check/libs/: More tests, prepare for tests with switching caps in buffer_alloc.

tests/check/libs/: More tests, prepare for tests with switching caps in buffer_alloc.

Original commit message from CVS:
* tests/check/libs/test_transform.c: (gst_test_trans_base_init),
(gst_test_trans_class_init), (result_sink_chain),
(result_buffer_alloc), (gst_test_trans_new), (gst_test_trans_free),
(gst_test_trans_push), (gst_test_trans_pop):
* tests/check/libs/transform1.c: (buffer_alloc_pt1),
(set_caps_pt1), (GST_START_TEST), (set_caps_pt2), (transform_ip_1),
(set_caps_1), (set_caps_ct1), (transform_ct1),
(transform_caps_ct1), (transform_size_ct1), (buffer_alloc_ct1),
(set_caps_ct2), (transform_ct2), (transform_caps_ct2),
(transform_size_ct2), (buffer_alloc_ct2),
(gst_basetransform_suite):
More tests, prepare for tests with switching caps in buffer_alloc.