X11Utils: Remove unneeded SendButtonEvent / SendKeyEvent utilities

[magcius]

This was used to send fake button or key events to every backend to
implement freelook. When I ported these to be based on wx events in
commit 5248211, I didn't realize that these were now unused, so I didn't
remove them. Do that now.

[delroth]

How does that work with freelook on nogui?

[magcius]

It doesn't. Nobody ever wrote the code to support freelook on NoGUI.

[delroth]

I thought that was the whole point of that code you're removing?

[magcius]

I don't see how that has anything to do with it, given that these helpers are being called from Frame.cpp, which isn't built in nogui mode.

And even if somebody wrote the code to make it work on nogui, it wouldn't need these helpers anyway, since the events would come from the native window system, not from a wx event loop that isn't running.

[delroth]

I see. Thanks for clarifying this.

[lioncash]

Looks good to me