decoder/flac: don't use float to calculate song duration

Simple (up-rounding) integer division is good enough.  We're casting
the result back to an integer anyway.

src/decoder/oggflac_plugin.c

@@ -172,9 +172,7 @@ static void of_metadata_dup_cb(G_GNUC_UNUSED const OggFLAC__SeekableStreamDecode
 
 	switch (block->type) {
 	case FLAC__METADATA_TYPE_STREAMINFO:
-		data->tag->time = ((float)block->data.stream_info.
-				   total_samples) /
-		    block->data.stream_info.sample_rate + 0.5;
+		data->tag->time = flac_duration(&block->data.stream_info);
 		return;
 	case FLAC__METADATA_TYPE_VORBIS_COMMENT:
 		flac_vorbis_comments_to_tag(data->tag, NULL,