OpenALBindings: fix crash on HL when passing NULL device

Author: ACrazyTown

project/src/media/openal/OpenALBindings.cpp

@@ -3388,7 +3388,7 @@ namespace lime {
 
 	HL_PRIM vbyte* HL_NAME(hl_alc_get_string) (HL_CFFIPointer* device, int param) {
 
-		ALCdevice* alcDevice = (ALCdevice*)device->ptr;
+		ALCdevice* alcDevice = device ? (ALCdevice*)device->ptr : 0;
 		const char* result = alcGetString (alcDevice, param);
 		int length = strlen (result);
 		char* _result = (char*)malloc (length + 1);