Implement wxTextEntry::SetHint() natively for GTK+3.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75335 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/textentry.h

@@ -48,6 +48,11 @@ public:
 
     virtual void SetMaxLength(unsigned long len);
 
+#ifdef __WXGTK3__
+    virtual bool SetHint(const wxString& hint);
+    virtual wxString GetHint() const;
+#endif
+
     // implementation only from now on
     void SendMaxLenEvent();
     bool GTKEntryOnInsertText(const char* text);