This allows us to pick GLX on X11 and EGL on Wayland
at runtime when building with wxWidgets 3.3.2+
GLEW only allowed to choose between GLX/EGL at compile time.
This also removes KICAD_USE_EGL option, KiCad will use
whatever wxWidgets was built with.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/20647
Alex Shvartzkop
3fa40e05dc