configure.ac: relax the check warning for gmtime_[rs] and localtime_[rs]…

[jimklimov]

…as long as we have one, it is okay

Closes: #2115

[desertwitch]

I came up with a similar solution:

AC_CHECK_FUNCS(strtok_r fileno sigemptyset sigaction,
        [], [AC_MSG_WARN([Required C library routine not found; try adding -D_POSIX_C_SOURCE=200112L])])

AC_CHECK_FUNCS(localtime_r localtime_s)
if test "x${ac_cv_func_localtime_r}" != xyes && test "x${ac_cv_func_localtime_s}" != xyes; then
        AC_MSG_WARN([Required C library routine not found; try adding -D_POSIX_C_SOURCE=200112L])
fi

AC_CHECK_FUNCS(gmtime_r gmtime_s)
if test "x${ac_cv_func_gmtime_r}" != xyes && test "x${ac_cv_func_gmtime_s}" != xyes; then
        AC_MSG_WARN([Required C library routine not found; try adding -D_POSIX_C_SOURCE=200112L])
fi

But while I was figuring out how to sign off my commit you were faster.
... and I like your solution better - so I've since tested your PR and it builds nicely now. ;-)

[jimklimov]

FYI: For just signing off, there is the -s argument (to commit, amend, rebase, etc.)

For more hassle about authored code provenance, see if https://github.com/networkupstools/nut/wiki/Code-contributions,-PRs,-PGP-and-DCO helps (welcome to amend if not) :)