[MOVED FROM BAD] configure.ac: Enable cdaudio and y4m.

[MOVED FROM BAD] configure.ac: Enable cdaudio and y4m.

Original commit message from CVS:
Patch by: Mark Nauwelaerts <manauw at skynet be>
* configure.ac:
Enable cdaudio and y4m.
* gst/y4m/Makefile.am:
* gst/y4m/gsty4mencode.c: (gst_y4m_encode_base_init),
(gst_y4m_encode_class_init), (gst_y4m_encode_init),
(gst_y4m_encode_reset), (gst_y4m_encode_setcaps),
(gst_y4m_encode_get_stream_header),
(gst_y4m_encode_get_frame_header), (gst_y4m_encode_chain),
(gst_y4m_encode_set_property), (gst_y4m_encode_get_property),
(gst_y4m_encode_change_state), (plugin_init):
* gst/y4m/gsty4mencode.h:
Port of y4mencode to 0.10.