lib/54300: lib/libutil/t_snprintb test regression on sparc

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

>Number:         54300
>Category:       lib
>Synopsis:       lib/libutil/t_snprintb test regression on sparc
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 17 11:30:01 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2019.04.27.17.45.28
>Organization:

>Environment:
System: NetBSD
Architecture: sparc
Machine: sparc
>Description:

Both test cases of the lib/libutil/t_snprintb test are failing on
sparc.

The snprintb test case fails with the message

   t_snprintb.c: res != buf (0x1<FOO=0x1=ONE> != 0x1<FOO=0x100000000=ONE>)

and the snprintb_m test case fais with 

  t_snprintb.c:111: len != res_len

Log output from a recent failure:

  http://releng.netbsd.org/b5reports/sparc/2019/2019.06.15.15.22.56/test.html#lib_libutil_t_snprintb_snprintb

The failures started started with with this commit:

  2019.04.27.17.45.28 christos src/common/lib/libutil/snprintb.c 1.19

>How-To-Repeat:

>Fix: