Add support for secure views.

Added the MotionEvent.FLAG_WINDOW_IS_OBSCURED flag which is set by the
input manager whenever another visible window is partly or wholly obscured
the target of a touch event so that applications can filter touches
accordingly.

Added a "filterTouchesWhenObscured" attribute to View which can be used to
enable filtering of touches when the view's window is obscured.

Change-Id: I936d9c85013fd2d77fb296a600528d30a29027d2
diff --git a/native/android/input.cpp b/native/android/input.cpp
index c79f913..57f0072 100644
--- a/native/android/input.cpp
+++ b/native/android/input.cpp
@@ -84,6 +84,10 @@
     return static_cast<const MotionEvent*>(motion_event)->getAction();
 }
 
+int32_t AMotionEvent_getFlags(const AInputEvent* motion_event) {
+    return static_cast<const MotionEvent*>(motion_event)->getFlags();
+}
+
 int32_t AMotionEvent_getMetaState(const AInputEvent* motion_event) {
     return static_cast<const MotionEvent*>(motion_event)->getMetaState();
 }