gtk2 rbgtktextbuffer.c: drop GTK_CHECK_VERSION(2,10,0)
gtk2 rbgtkassistant.c: drop GTK_CHECK_VERSION(2,10,0)
gtk2 rbgtkpixmap.c: drop GTK_CHECK_VERSION(2,10,0)
gtk2 rbgtkrange.c: drop GTK_CHECK_VERSION(2,10,0)