First window doesn't show up on sbcl/windows

[3b]

SBCL is built as a console application on windows, and defaults to not showing the first window created. (Possibly only when started from a graphical application like emacs/slime?)

Workaround is to call (glut:show-window) when that happens, but possibly cl-glut could/should detect that situation and do so automatically?

see CreateWindow, ShowWindow, STARTUPINFO, GetStartupInfoW

(This isn't specific to cl-glut. cl-sdl2(lispgames/cl-sdl2#23), commonqt(commonqt/commonqt#24) etc have the same problem)

[3b]

If we try to fix this in cl-glut, need to be careful about the case where the user doesn't actually want the window shown to start with (assuming that is even possible?)