VC6 compilation fix: don't return void values.

Fix VC6 compilation broken by r66237: don't return the result from a void
function, this compiler doesn't support this C++ feature.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66246 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/msgdlg.cpp

@@ -610,7 +610,7 @@ void wxMessageDialog::DoCentre(int dir)
         return;
 #endif // wxHAS_MSW_TASKDIALOG
 
-    return wxMessageDialogBase::DoCentre(dir);
+    wxMessageDialogBase::DoCentre(dir);
 }
 
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