libs/gst/base/gstbasetransform.c: Cleanups, separate normal flow from errors, add...

libs/gst/base/gstbasetransform.c: Cleanups, separate normal flow from errors, add sensible

Original commit message from CVS:
* libs/gst/base/gstbasetransform.c:
(gst_base_transform_transform_caps),
(gst_base_transform_transform_size),
(gst_base_transform_prepare_output_buffer),
(gst_base_transform_get_unit_size),
(gst_base_transform_buffer_alloc),
(gst_base_transform_handle_buffer),
(gst_base_transform_change_state):
Cleanups, separate normal flow from errors, add sensible
DEBUG lines.
Don't try to renegotiate when allocating an output buffer.
Also copy DISCONT buffer flag when copying a buffer.
Reset the transform after we finish streaming, not during.