fix NPE

Change-Id: I2b17c110e30957e80da0b4aa77efd511e864d1b4

java/com/libremobileos/vncflinger/VncFlinger.java

@@ -261,7 +261,7 @@ public class VncFlinger extends Service {
 		quit();
 		if (mRemoteCursor)
 			((InputManager) getSystemService(INPUT_SERVICE)).setForceNullCursor(false);
-		if (mSupportClipboard)
+		if (mSupportClipboard && mClipboard != null && mClipListener != null)
 			mClipboard.removePrimaryClipChangedListener(mClipListener);
 		if (mDisplay != null)
 			mDisplay.release();