vt pdckbd (PDC_get_key): fix missing init warnings

[GitMensch]

fixes #373
some of the variables are passed as pointers to sub-functions but may not always be set - explicit initialize to fix the init-warning this results in

[Bill-Gray]

Good thought, but it just suppresses the warning; it doesn't fix the actual problem. The handling of window resizing on Microsoft Windows is a little flawed. We're checking the PDC_resize_occurred variable to see if the window is resized, and then calling the PDC_check_for_resize() function that sets it. This actually works, because we miss the resize at first and get it later, but it's not the right order of events.

[GitMensch]

I'll leave it to the expert :-)

If needed I possibly get back to the MSYS2 CI with PKGBUILD, but that would unlikely to be within the next 12 days.