tst-strerror not getting translations

[Samuel Thibault]

Hello,

It seems that tst-strerror is not getting the translated messages before
of misconfigured message file path. This shows up for instance by
configuring with

../configure --prefix=

and we see with

./testrun.sh --tool=strace $PWD/string/tst-strerror --direct

[...]
openat(AT_FDCWD, "/share/locale/pt_BR.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
[...]

And then the pt_BR message comparisons fail.

Samuel