input: prevent MBTN_LEFT conflict with VO dragging

Currently, the built-in VO dragging conflicts with the MBTN_LEFT binding,
so the binding is activated even though the VO dragging begins. Fix this
by releasing the currently down command so that MBTN_LEFT can be bound to
a useful action (such as play/pause).

input/input.c

@@ -922,6 +922,8 @@ static void set_mouse_pos(struct input_ctx *ictx, int x, int y)
     if (ictx->dragging_button_down && mouse_outside_dragging_deadzone) {
         // Begin built-in VO dragging if the mouse moves while the dragging button is down.
         ictx->dragging_button_down = false;
+        // Prevent activation of MBTN_LEFT key binding if VO dragging begins.
+        release_down_cmd(ictx, true);
         mp_cmd_t *drag_cmd = mp_input_parse_cmd(ictx, bstr0("begin-vo-dragging"), "<internal>");
         queue_cmd(ictx, drag_cmd);
     }