bug#63555: emacs 29 complains that it can't connect to the display

[Peter Oliver]

FWIW, here is a patch which causes Emacs to check that at least one of the 
environment variables WAYLAND_DISPLAY, DISPLAY, BROADWAY_DISPLAY is set before 
it will try to use PGTK for its initial window.

This patch is not suitable for merging, because it doesn’t consider what 
happens if you try to use PGTK on Windows or MacOS.  However, people might find 
it useful if they’re not using one of those platforms.

This patch depends on the patch for bug 72118.

--
Peter Oliver

0002-Fall-back-to-the-terminal-from-pure-GTK-when-no-disp.patch
Description: Text document