Add wxUSE_PRIVATE_FONTS and drop wxHAS_PRIVATE_FONTS

Handle this feature as all the other ones and provide a configure switch
and a setup.h option to disable it if necessary, as it may be desirable
to do it, especially under Linux, to avoid extra dependency on pangoft2
if this functionality is unnecessary.

src/osx/fontutil.cpp

@@ -69,6 +69,8 @@ wxString wxNativeEncodingInfo::ToString() const
 // Private Fonts
 // ----------------------------------------------------------------------------
 
+#if wxUSE_PRIVATE_FONTS
+
 // On OSX one can provide private fonts simply by putting the font files in
 // with the resources in your application bundle. So the API for adding fonts
 // does not do anything except checking that the file you pass to it actually
@@ -95,6 +97,8 @@ bool wxFontBase::AddPrivateFont(const wxString& filename)
     return true;
 }
 
+#endif // wxUSE_PRIVATE_FONTS
+
 // ----------------------------------------------------------------------------
 // helper functions
 // ----------------------------------------------------------------------------