refactor wxGTK mnemonics conversion functions in a separate file to be able to reuse them from wxMenu too

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49869 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/private/stattext.h

@@ -67,6 +67,8 @@ private:
     bool m_eol;
 };
 
+#endif // wxUSE_STATTEXT
+
 enum
 {
     wxMARKUP_ENTITY_AMP,
@@ -92,6 +94,4 @@ enum
 //
 extern const wxChar *wxMarkupEntities[wxMARKUP_ELEMENT_MAX][wxMARKUP_ENTITY_MAX];
 
-#endif // wxUSE_STATTEXT
-
 #endif // _WX_PRIVATE_STATTEXT_H_