configure.ac: bump required gstreamer version to 0.8.1.1 because of following changes...

configure.ac: bump required gstreamer version to 0.8.1.1 because of following changes [--ds]

Original commit message from CVS:
reviewed by David Schleef
* configure.ac: bump required gstreamer version to 0.8.1.1
because of following changes [--ds]
* gst-libs/gst/riff/riff-read.c:  Include gst/gstutils.h.
(gst_riff_peek_head, gst_riff_peek_list, gst_riff_read_list)
(gst_riff_read_header):  Use GST_READ_UINT*
macros to access possibly unaligned memory.
* gst/typefind/gsttypefindfunctions.c: Include gst/gstutils.h.
(mp3_type_find):  Use GST_READ_UINT*
macros to access possibly unaligned memory.
(mp3_type_find, mpeg1_parse_header, qt_type_find)
(speex_type_find): Likewise
* gst/tags/gstvorbistag.c: (ADVANCE): Likewise
* gst/qtdemux/qtdemux.c: Include stdlib.h (needed by realloc).
(QTDEMUX_GUINT32_GET, QTDEMUX_GUINT16_GET, QTDEMUX_FP32_GET)
(QTDEMUX_FP16_GET, QTDEMUX_FOURCC_GET)
(gst_qtdemux_loop_header, gst_qtdemux_loop_header)
(qtdemux_node_dump_foreach, qtdemux_tree_get_child_by_type)
(qtdemux_tree_get_sibling_by_type):  Use GST_READ_UINT*
macros to access possibly unaligned memory.
* gst/mpegstream/gstmpegpacketize.c: (parse_generic, parse_chunk):
Likewise.
* gst/mpegstream/gstmpegdemux.c: (gst_mpeg_demux_parse_syshead)
(gst_mpeg_demux_parse_packet, gst_mpeg_demux_parse_pes): Likewise.
* gst/mpegaudioparse/gstmpegaudioparse.c: (gst_mp3parse_chain):
Likewise.
* gst/mpeg2sub/gstmpeg2subt.c: (GST_BUFFER_DATA)
(gst_mpeg2subt_chain_subtitle): Likewise.
* gst/mpeg1videoparse/gstmp1videoparse.c: (mp1videoparse_parse_seq)
(gst_mp1videoparse_time_code, gst_mp1videoparse_real_chain):
Likewise.
* gst/mpeg1sys/buffer.c: (mpeg1mux_buffer_update_audio_info):
Likewise.
* gst/cdxaparse/gstcdxaparse.c: (gst_bytestream_peek_bytes):
Likewise.
* gst/asfdemux/gstasfdemux.c: (_read_var_length, _read_uint):
Likewise.