Fix leaks some more.

Fix leaks some more.

Original commit message from CVS:
* ext/amrnb/amrnbdec.c: (gst_amrnbdec_init):
* gst/ac3parse/gstac3parse.c: (gst_ac3parse_init):
* gst/asfdemux/gstasfmux.c: (gst_asfmux_init):
* gst/dvdlpcmdec/gstdvdlpcmdec.c: (gst_dvdlpcmdec_init):
* gst/dvdsub/gstdvdsubdec.c: (gst_dvd_sub_dec_init):
* gst/iec958/ac3iec.c: (ac3iec_init):
* gst/mpegstream/gstrfc2250enc.c: (gst_rfc2250_enc_init):
Fix leaks some more.