[sldev] Shortcut keys for rendering features

[Soft Linden]

I recently accepted a patch that remaps some of the debug mode graphic
features from CTRL-ALT-(number) to CTRL-ALT-(function key number) in
order to avoid problems with international keyboards under Windows.
The problem is that the *new* key sequences overlap what xfree86/xorg
use for reaching virtual consoles.

I'd like to keep these consistent and accessible across all platforms,
even if they're hidden debug settings, so before I make another
change:

Is there any special global mapping for CTRL-SHIFT-(function key
number) on any platform?