Exit dialog: use Layout on the whole window

Prevents mislaignment in footpritn editor on close with unsaved
changes.

Fixes: lp:1813961
* https://bugs.launchpad.net/kicad/+bug/1813961

common/confirm.cpp

@@ -167,8 +167,7 @@ public:
         m_sdbSizer1Cancel->SetLabel( aCancelLabel );
         m_sdbSizer1OK->SetDefault();
 
-        m_sdbSizer1->Layout();
-        m_buttonSizer->Layout();
+        Layout();
 
         FinishDialogSettings();
     };