Fix cfg feature compile bug

Cargo.toml

@@ -82,7 +82,7 @@ image = ["png"]
 image-jpg = ["mozjpeg"]
 image-webp = ["webp"]
 lossless-audio = ["utils-pcm"]
-audio-flac = ["libflac-sys"]
+audio-flac = ["libflac-sys", "utils-pcm"]
 unstable = ["msg_tool_macro/unstable"]
 # utils feature
 utils-bit-stream = []

src/utils/lossless_audio.rs

@@ -1,4 +1,5 @@
 //! Lossless audio utilities.
+#[cfg(feature = "audio-flac")]
 use super::flac::*;
 use super::pcm::*;
 use crate::types::*;
@@ -13,6 +14,7 @@ pub fn write_audio<W: Write + Seek, R: Read>(
 ) -> Result<()> {
     match config.lossless_audio_fmt {
         LosslessAudioFormat::Wav => write_pcm(header, reader, writer)?,
+        #[cfg(feature = "audio-flac")]
         LosslessAudioFormat::Flac => write_flac(header, reader, writer, config)?,
     }
     Ok(())