[Issue 21113] std.file.thisExePath on NetBSD depends upon the /proc filesystem

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21113

--- Comment #1 from Euan Torano <euan+dlang-bugzilla at torano.co.uk> ---
I also noticed that DragonFlyBSD is using procfs too, but has the same sysctl
as FreeBSD (though numbered differently of course...):
https://man.dragonflybsd.org/?command=sysctl&section=3

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