sys/oss/gstosselement.c: Add code to handle rate probing (bug #120883)

sys/oss/gstosselement.c: Add code to handle rate probing (bug #120883)

Original commit message from CVS:
* sys/oss/gstosselement.c: (gst_osselement_sync_parms),
(gst_osselement_close_audio), (gst_osselement_probe_caps),
(gst_osselement_get_format_structure),
(gst_osselement_rate_probe_check), (gst_osselement_rate_add_range),
(gst_osselement_rate_check_rate), (gst_osselement_rate_add_rate),
(gst_osselement_rate_int_compare): Add code to handle rate probing
(bug #120883)
* sys/oss/gstosselement.h: same
* sys/oss/gstosssink.c: (gst_osssink_init), (gst_osssink_getcaps):
Use rate probing provided by osselement.
* sys/oss/gstosssrc.c: (gst_osssrc_init), (gst_osssrc_getcaps): same