Marking old window variables obsolete

[Chong Yidong]

The new display-buffer machinery still supports the following variables:

special-display-buffer-names
special-display-regexps
special-display-frame-alist
special-display-function
same-window-buffer-names
same-window-regexps
display-buffer-reuse-frames

I think we can mark these as obsolete for 24.2.  Any objections?

There's also pop-up-frames and pop-up-windows, but I think we can wait a
few releases before marking those as obsolete.