Explicitly indicate when device clipboard is set

Pass the information that device clipboard has been set to the key
processor. This avoids the keyprocessor to "guess", and paves the way to
implement a proper acknowledgement mechanism.

PR #2814 <https://github.com/Genymobile/scrcpy/pull/2814>

app/src/keyboard_inject.c

@@ -188,7 +188,13 @@ convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to,
 
 static void
 sc_key_processor_process_key(struct sc_key_processor *kp,
-                             const SDL_KeyboardEvent *event) {
+                             const SDL_KeyboardEvent *event,
+                             bool device_clipboard_set) {
+    // The device clipboard synchronization and the key event messages are
+    // serialized, there is nothing special to do to ensure that the clipboard
+    // is set before injecting Ctrl+v.
+    (void) device_clipboard_set;
+
     struct sc_keyboard_inject *ki = DOWNCAST(kp);
 
     if (event->repeat) {