core: add additional headers for Popup.cpp and InputMethodRelay.hpp (#4909)

src/desktop/Popup.cpp

@@ -1,4 +1,5 @@
 #include "Popup.hpp"
+#include "../Compositor.hpp"
 
 CPopup::CPopup(CWindow* pOwner) : m_pWindowOwner(pOwner) {
     initAllSignals();
@@ -232,4 +233,4 @@ void CPopup::recheckChildrenRecursive() {
 
 Vector2D CPopup::size() {
     return m_vLastSize;
-}
+}