gtk2 rbgdkdragcontext.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgdkwindow.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgdkevent.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgdkdraw.c: drop GTK_CHECK_VERSION(2,6,0)
gtk2 rbgdkpangorenderer.c: drop GTK_CHECK_VERSION(2,6,0)
Merge pull request #188 from cosmo0920/drop-gtk2.6.0-macro-gdk-part

drop GTK_CHECK_VERSION(2,6,0) macro in gtk2/rbgdk*.c

Patch by cosmo. Thanks!!!