Ensure header guards enclose entire header.

drivers/alsa/audio_driver_alsa.h

@@ -28,11 +28,11 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 
-#ifdef ALSA_ENABLED
-
 #ifndef AUDIO_DRIVER_ALSA_H
 #define AUDIO_DRIVER_ALSA_H
 
+#ifdef ALSA_ENABLED
+
 #include "core/os/mutex.h"
 #include "core/os/thread.h"
 #include "servers/audio_server.h"
@@ -88,6 +88,6 @@ public:
 	~AudioDriverALSA() {}
 };
 
-#endif // AUDIO_DRIVER_ALSA_H
-
 #endif // ALSA_ENABLED
+
+#endif // AUDIO_DRIVER_ALSA_H