When unsetting DISPLAY, Wine hangs after executing a command, and doesn't
allow for other instances of wine to start, i.e. games do not launch, with
a cryptic error. This also fixes the previously observed issues with
`winepath.exe` and `reg.exe` never exiting.
This is likely due to the newly introduced Wayland driver. This behavior
can be observed when Wayland support is compiled into Wine and the wayland
driver is enabled in the prefix's registry. In this case, if running under
X11 and DISPLAY is not set, Wine will hang, and the process never returns.
