Control: Change internal interfaces to batch-process input axis updates

These naturally come in bunches on many platforms like Android, so lay
some groundwork to also handle them in bunches to minimize locking in
the future.

Linux buildfix

Windows/DinputDevice.cpp

@@ -208,7 +208,7 @@ void SendNativeAxis(InputDeviceID deviceId, int value, int &lastValue, InputAxis
 	axis.deviceId = deviceId;
 	axis.axisId = axisId;
 	axis.value = (float)value * (1.0f / 10000.0f); // Convert axis to normalised float
-	NativeAxis(axis);
+	NativeAxis(&axis, 1);
 
 	lastValue = value;
 }
@@ -241,6 +241,7 @@ int DinputDevice::UpdateState() {
 	ApplyButtons(js);
 
 	if (analog)	{
+		// TODO: Use the batched interface.
 		AxisInput axis;
 		axis.deviceId = DEVICE_ID_PAD_0 + pDevNum;