Re: kern/52598 (/proc/self/exe misbehaves if it's on a null mount)

[Frédéric Fauberteau <triaxx%NetBSD.org@localhost>]

The following change fix the crash:
-cvs rdiff -u -r1.442.4.3 -r1.450 src/sys/kern/kern_exec.c
+cvs rdiff -u -r1.442.4.3 -r1.454 src/sys/kern/kern_exec.c

Before the christos modifications, lang/rust building failed on NetBSD 
8.0 when done in a chroot environment:
--- stderr
thread 'main' panicked at 'failed to get current_exe: /proc/curproc/exe 
doesn't point to regular file.', 
src/librustc/session/filesearch.rs:167:23

Now, it builds successfully:
$ ls -1 /mnt/ccd0/sandbox/nbsd8-hydralisk/pkg/All | grep rust
rust-1.40.0.tgz

The current status of this PR is 'needs-pullups'. What could we do to 
close it?

My personal need is to have a 8.0 able to build bulk sets of packages 
for several 8.0 domU. If theses changes can only be integrated in 8.2, I 
finally should upgrade all my 8.0 to 8.2. I would to avoid upgrading but 
if I have to do, I might as well do it to 9.0. So I can continue while 
waiting with my custom 8.0. Is there a need to add this fix in a future 
8.X release? In this case, what should I provide to contribute?