Arsenal - Fix main menu mission

[PabstMirror]

Fix #7584

• Macros broke loading the mission's XEH_preInit
• With double killed XEH, 2nd time it's now objNull and threw script error because of a
  missionNamespace setvariable [_varName

edit: I still think setting objNull is the best solution to the double killed xeh, just need to watch out for odd uses like this one

[commy2]

Why is COMPILE_FILE() broken?

[jonpas]

It's a mission and doesn't include it?

[PabstMirror]

file path is addons/arsenal/missions/Arsenal.VR/CfgEventHandlers.hpp
it's a mission inside of a addon
we just want the mission files, not the base addon

[commy2]

Ah, I see. One is a folder from addon space, while the PR is from mission space (no leading slash + no file that matches the path in addon space).

Maybe could use a comment.