Port jpegdec to 0.9; handles 'progressive loading' now, ie. input does no longer need to be one single buffer.

Original commit message from CVS:
* configure.ac:
* ext/Makefile.am:
* ext/jpeg/Makefile.am:
* ext/jpeg/gstjpeg.c: (plugin_init):
* ext/jpeg/gstjpegdec.c: (gst_jpeg_dec_get_type),
(gst_jpeg_dec_finalize), (gst_jpeg_dec_base_init),
(gst_jpeg_dec_class_init), (gst_jpeg_dec_fill_input_buffer),
(gst_jpeg_dec_init_source), (gst_jpeg_dec_skip_input_data),
(gst_jpeg_dec_resync_to_restart), (gst_jpeg_dec_term_source),
(gst_jpeg_dec_my_output_message), (gst_jpeg_dec_my_emit_message),
(gst_jpeg_dec_my_error_exit), (gst_jpeg_dec_init),
(is_jpeg_start_marker), (is_jpeg_end_marker),
(gst_jpeg_dec_find_jpeg_header), (gst_jpeg_dec_ensure_header),
(gst_jpeg_dec_have_end_marker),
(gst_jpeg_dec_parse_tag_has_entropy_segment),
(gst_jpeg_dec_parse_image_data), (gst_jpeg_dec_chain),
(gst_jpeg_dec_change_state):
* ext/jpeg/gstjpegdec.h:
Port jpegdec to 0.9; handles 'progressive loading' now, ie. input does
no longer need to be one single buffer.