Warnings from %m in refclock_oncore (some systems)

../../ntpd/refclock_oncore.c: In function 'oncore_start':
../../ntpd/refclock_oncore.c:677:9: warning: %m is only allowed in syslog(3) like functions [-Wformat=]
         device2, errno);
         ^
../../ntpd/refclock_oncore.c: In function 'oncore_ppsapi':
../../ntpd/refclock_oncore.c:844:3: warning: %m is only allowed in syslog(3) like functions [-Wformat=]
   oncore_log_f(instance, LOG_ERR, "time_pps_getcap failed: %m");
   ^

6 more.

I've seen it on NetBSD and FreeBSD Checking for %m expansion in vsnprintf says "no" on Alpine Linux but doesn't build Oncore because ppsapi is missing on that box. gcc (Alpine 6.4.0) 6.4.0