gtk2 rbgtkmenu.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkcellrendererprogress.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkdrag.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkstock.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkfilechooserbutton.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkicontheme.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkselectiondata.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkliststore.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkdragcontext.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtktreeview.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkcellrenderercombo.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkentrycompletion.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkdialog.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtkcombobox.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgtktextbuffer.c: drop GTK_CHECK_VERSION(2,6,0)