Scale mouse events

The video screen size on the client may differ from the real device
screen size (e.g. the video stream may be scaled down). As a
consequence, mouse events must be scaled to match the real device
coordinates.

For this purpose, make the client send the video screen size along with
the absolute pointer location, and the server scale the location to
match the real device size before injecting mouse events.

app/src/controlevent.h

@@ -6,6 +6,7 @@
 
 #include "android/input.h"
 #include "android/keycodes.h"
+#include "common.h"
 
 #define CONTROL_EVENT_QUEUE_SIZE 64
 #define SERIALIZED_EVENT_MAX_SIZE 33
@@ -32,12 +33,10 @@ struct control_event {
         struct {
             enum android_motionevent_action action;
             enum android_motionevent_buttons buttons;
-            Sint32 x;
-            Sint32 y;
+            struct point point;
         } mouse_event;
         struct {
-            Sint32 x;
-            Sint32 y;
+            struct point point;
             Sint32 hscroll;
             Sint32 vscroll;
         } scroll_event;