mgw: accept zero-length RTP payload as BFI Mainline OsmoBTS now has an option (rtp continuous-streaming) that causes it to emit an RTP packet every 20 ms without gaps, sending a BFI marker in the form of zero-length RTP payload when it has nothing else to send. These codec-independent BFI markers don't indicate TAF, but this provision is a good start. Accept this BFI packet format in themwi-mgw.

/*
 * This header file defines structures written into the binary form
 * of the number database file.
 */

struct numdb_file_hdr {
	uint32_t	owned_number_count;
	uint32_t	short_number_count;
};

struct short_number_map {
	uint32_t	short_code;
	uint32_t	prefix;
};