fix warnings

src/audio/AL/ALAudio.cpp

@@ -74,8 +74,7 @@ ALInputDevice::ALInputDevice(
     uint bitsPerSample,
     uint sampleRate
 )
-    : al(al),
-      device(device),
+    : device(device),
       channels(channels),
       bitsPerSample(bitsPerSample),
       sampleRate(sampleRate) {

src/audio/AL/ALAudio.hpp

@@ -108,7 +108,6 @@ namespace audio {
 
         size_t read(char* buffer, size_t bufferSize) override;
     private:
-        ALAudio* al;
         ALCdevice* device;
         uint channels;
         uint bitsPerSample;