Fix a free format mp3 files

[StudioMaX]

While analyzing warnings in new php versions, I found erroneous behavior in my opinion.

According to this part:

getID3/getid3/module.audio.mp3.php

Lines 916 to 926 in a99e0a2

	// LAME CBR
	if ($thisfile_mpeg_audio_lame_raw['vbr_method'] == 1) {
	$thisfile_mpeg_audio['bitrate_mode'] = 'cbr';
	$thisfile_mpeg_audio['bitrate'] = self::ClosestStandardMP3Bitrate($thisfile_mpeg_audio['bitrate']);
	$info['audio']['bitrate'] = $thisfile_mpeg_audio['bitrate'];
	//if (empty($thisfile_mpeg_audio['bitrate']) || (!empty($thisfile_mpeg_audio_lame['bitrate_min']) && ($thisfile_mpeg_audio_lame['bitrate_min'] != 255))) {
	// $thisfile_mpeg_audio['bitrate'] = $thisfile_mpeg_audio_lame['bitrate_min'];
	//}
	}

The self::ClosestStandardMP3Bitrate method will be called, which is passed the $thisfile_mpeg_audio['bitrate'] argument. In the case when $thisfile_mpeg_audio['bitrate'] is equal to free then method self::ClosestStandardMP3Bitrate will return - and this value will be written to $info['audio']['bitrate'] and $thisfile_mpeg_audio['bitrate'].

By additional checking that the bitrate is not equal to free, we prevent writing to $info['audio']['bitrate'] an incorrect value -, since the correctly calculated bitrate is already there.

Could you please confirm my guesses?

Sample (and some others in mp3/freeformat): https://github.com/JamesHeinrich/getID3-testfiles/raw/master/mp3/freeformat/3903d-freeformat384.mp3

[JamesHeinrich]

Looks good to me, thanks.