Add support for AMR-NB (mobile phone audio format; #155163, #163286).

Add support for AMR-NB (mobile phone audio format; #155163, #163286).

Original commit message from CVS:
* configure.ac:
* ext/Makefile.am:
* ext/amrnb/Makefile.am:
* ext/amrnb/amrnb.c: (plugin_init):
* ext/amrnb/amrnbdec.c: (gst_amrnbdec_get_type),
(gst_amrnbdec_base_init), (gst_amrnbdec_class_init),
(gst_amrnbdec_init), (gst_amrnbdec_link), (gst_amrnbdec_chain),
(gst_amrnbdec_state_change):
* ext/amrnb/amrnbdec.h:
* ext/amrnb/amrnbparse.c: (gst_amrnbparse_get_type),
(gst_amrnbparse_base_init), (gst_amrnbparse_class_init),
(gst_amrnbparse_init), (gst_amrnbparse_formats),
(gst_amrnbparse_querytypes), (gst_amrnbparse_query),
(gst_amrnbparse_handle_event), (gst_amrnbparse_reserve),
(gst_amrnbparse_loop), (gst_amrnbparse_state_change):
* ext/amrnb/amrnbparse.h:
Add support for AMR-NB (mobile phone audio format; #155163, #163286).
* gst/typefind/gsttypefindfunctions.c: (plugin_init):
Add AMR-NB/-WB raw formats.
* ext/alsa/gstalsa.c: (gst_alsa_link):
Keep valid time when changing format.
* gst/qtdemux/qtdemux.c: (gst_qtdemux_loop_header),
(qtdemux_parse_trak):
Add some more format-specific options (#140141, #143555, #155163).