[clang-tidy] remove misplaced const

The rhs evaluates to void *const, not const void*.

Found with misc-misplaced-const

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/decoder/plugins/AudiofileDecoderPlugin.cxx

@@ -200,7 +200,7 @@ audiofile_stream_decode(DecoderClient &client, InputStream &is)
 	AudioFileInputStream afis{&client, is};
 	AFvirtualfile *const vf = setup_virtual_fops(afis);
 
-	const AFfilehandle fh = afOpenVirtualFile(vf, "r", nullptr);
+	auto fh = afOpenVirtualFile(vf, "r", nullptr);
 	if (fh == AF_NULL_FILEHANDLE)
 		return;