drop GTK_CHECK_VERSION(2,2,0) macro in gtk2/gdk*.c

As discussed in issue #182, I dropped GTK_CHECK_VERSION(2,2,0) macro in gtk2.
* This pull request contains file changes related to GTK_CHECK_VERSION(2,2,0) only in gtk2/gdk*.c.

When I delete all at once GTK_CHECK_VERSION(2,2,0) macro sections, it is __too big file changes__ to open pull request, I think.

So, I split gdk*.c part and gtk*.c part.
I'll send pull request related to another part later.