Provide wxGetKeyState() studfor wxGTK under Windows.

Under Unix this function is implemented in X11-specific code, so provide a
stub under Windows to at least avoid link errors.

Closes #14409.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71793 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -2081,6 +2081,16 @@ wxWindow *wxGetActiveWindow()
 }
 
 
+// Under Unix this is implemented using X11 functions in utilsx11.cpp but we
+// need to have this function under Windows too, so provide at least a stub.
+#ifdef __WINDOWS__
+bool wxGetKeyState(wxKeyCode WXUNUSED(key))
+{
+    wxFAIL_MSG(wxS("Not implemented under Windows"));
+    return false;
+}
+#endif // __WINDOWS__
+
 wxMouseState wxGetMouseState()
 {
     wxMouseState ms;