tag_id3: parse ID3 tags in AIFF files

Added a small AIFF parser library, code copied from the RIFF parser
(big-endian integers).  Look for an "ID3" chunk, and let libid3tag
parse it.

src/riff.c

@@ -86,8 +86,6 @@ riff_seek_id3(FILE *file)
 			/* pad byte */
 			++size;
 
-		g_debug("chunk='%.4s' size=%zu\n", chunk.id, size);
-
 		if (memcmp(chunk.id, "id3 ", 4) == 0)
 			/* found it! */
 			return size;