MusicChunk: make the struct size exactly 4096

src/MusicChunk.hxx

@@ -124,7 +124,7 @@ struct MusicChunkInfo {
  */
 struct MusicChunk : MusicChunkInfo {
 	/** the data (probably PCM) */
-	uint8_t data[CHUNK_SIZE];
+	uint8_t data[CHUNK_SIZE - sizeof(MusicChunkInfo)];
 
 	/**
 	 * Prepares appending to the music chunk.  Returns a buffer
@@ -153,4 +153,6 @@ struct MusicChunk : MusicChunkInfo {
 	bool Expand(AudioFormat af, size_t length) noexcept;
 };
 
+static_assert(sizeof(MusicChunk) == CHUNK_SIZE, "Wrong size");
+
 #endif