disable gcc warning about class having private dtors and no friends (patch 1065318)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@30953 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

build/bakefiles/common.bkl

@@ -388,6 +388,9 @@ $(TAB)copy "$(DOLLAR)(InputPath)" $(SETUPHDIR)\wx\setup.h
             -wcd=657 <!-- define this function inside its class definition (could have improved code quality) -->
             -wcd=667 <!-- 'va_start' macro will not work without an argument before '...' -->
         </cppflags-watcom>
+        <cppflags-mingw>
+            -Wno-ctor-dtor-privacy <!-- only defines a private destructor and has no friends -->
+        </cppflags-mingw>
     </template>
 
     <!-- for both GUI and wxBase libs/samples: -->