misc/55757: Builds fail to clean up temporary files

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         55757
>Category:       misc
>Synopsis:       Builds fail to clean up temporary files
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 27 10:10:00 +0000 2020
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current (target), NetBSD-9 (host)
>Organization:
>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

Both the TNF testbed and my own are accumulating new files in /tmp
every time they do a build.  For example, on my testbed, after the
latest amd64 release build, which was successful, the following files
remain in /tmp:

  -rw-------    1 gson  wheel     126453 Oct 27 01:02 ccpGAqy9.ld
  -rw-------    1 gson  wheel          0 Oct 27 01:02 ccdid22o.le
  -rw-------    1 gson  wheel          0 Oct 27 01:02 ccHFelWv.cdtor.o
  -rw-------    1 gson  wheel          0 Oct 27 01:02 ccCBtXvF.cdtor.c

The build command was one with TMPDIR=/tmp; the full build command was:

   build.sh -j 24 -D /tmp/build/2020.10.26.21.34.10-amd64-baremetal/destdir -R /bracket/amd64-baremetal/test/2020.10.26.21.34.10/release -T /tmp/build/2020.10.26.21.34.10-amd64-baremetal/tools -O /tmp/build/2020.10.26.21.34.10-amd64-baremetal/obj -m amd64 -V TMPDIR=/tmp -x -U release sourcesets

>How-To-Repeat:

>Fix: