[gparted] Use Gtk::Separator (!25)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 1bee0ddf2605ce2d0882e77cb4f58a33f0141de4
Author: Luca Bacci <luca bacci982 gmail com>
Date:   Wed Feb 27 17:59:20 2019 +0100

    Use Gtk::Separator (!25)
    
    Gtk::HSeparator was deprecated in Gtkmm 3.2.  Replace with plain
    Gtk::Separator.
    
    Closes !25 - Modern Gtk3 - part 1

 src/Win_GParted.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/Win_GParted.cc b/src/Win_GParted.cc
index 1ebaaf1c..1d600756 100644
--- a/src/Win_GParted.cc
+++ b/src/Win_GParted.cc
@@ -3501,7 +3501,7 @@ bool Win_GParted::remove_non_empty_lvm2_pv_dialog( const OperationType optype )
        // text in the dialog.
        Gtk::Box * msg_area = dialog .get_message_area() ;
 
-       Gtk::HSeparator * hsep( manage( new Gtk::HSeparator() ) ) ;
+       Gtk::Separator *hsep(manage(new Gtk::Separator(Gtk::ORIENTATION_HORIZONTAL)));
        msg_area ->pack_start( * hsep ) ;
 
        Gtk::Table * table( manage( new Gtk::Table() ) ) ;