bin/55810: usr.bin/make/t_make:objdir_writable test case fails

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

>Number:         55810
>Category:       bin
>Synopsis:       usr.bin/make/t_make:objdir_writable test case fails
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 17 17:45:00 +0000 2020
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current
>Organization:
>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

The usr.bin/make/t_make:objdir_writable test case is failing on multiple
testbeds.  It already failed in the first successful build after it was
added.

Log output from a recent failure is here:

  http://releng.netbsd.org/b5reports/i386/2020/2020.11.17.10.49.41/test.html#usr.bin_make_t_make_objdir_writable

>How-To-Repeat:

Run the ATF tests.

>Fix: