Rename wxWindow::GetMainWindow() to X11GetMainWindow() in wxX11.

This avoids conflicts with GetMainWindow() defined in other wxWindow-derived
classes (such as wxDataViewCtrl and potentially user-defined classes as well).

Closes #11818.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63723 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/x11/reparent.h

@@ -60,7 +60,7 @@ class WXDLLIMPEXP_CORE wxAdoptedWindow: public wxWindow
     virtual ~wxAdoptedWindow();
 
     void SetHandle(WXWindow window) { m_mainWindow = window; m_clientWindow = window; }
-    WXWindow GetHandle() const { return GetMainWindow(); }
+    WXWindow GetHandle() const { return X11GetMainWindow(); }
 };
 
 #endif