[gtkada] bug in function Gtk.Main.Check_Version (gtkada 2.24.10)

[François FABIEN]

Hello,

Working with version 2.24.10, the behavior of Gtk.Main.Check_Version 
when the check is OK is incorrect.
>    --  Return value: %NULL if the GTK+ library is compatible with the 
> given
>    --  version, or a string describing the version mismatch.
In fact, it should return an Empty String instead when compatible.

Presently, when check is OK throws an exception 
INTERFACES.C.STRINGS.DEREFERENCE_ERROR
Yous should check  if
     Internal (Required_Major, Required_Minor, Required_Micro)

is null, before taking the Value.

Regards

F. Fabien.