NTPsec does not build on CentOS 6.x

waf configure ends this way:

Checking for header sys/timepps.h : no Checking for header event2/event.h : not found

The root cause is that although CentOS 6 has libevent, it does not have anywhere near the same contents as that on CentOS 7 or Fedora.

[joel@localhost ntpsec]$ rpm -ql libevent-devel /usr/bin/event_rpcgen.py /usr/lib/libevent.a /usr/lib/libevent.so /usr/lib/libevent_core.a /usr/lib/libevent_core.so /usr/lib/libevent_extra.a /usr/lib/libevent_extra.so /usr/share/man/man3/evdns.3.gz /usr/share/man/man3/event.3.gz [joel@localhost ntpsec]$ rpm -ql libevent-headers /usr/include/evdns.h /usr/include/event-config.h /usr/include/event.h /usr/include/evhttp.h /usr/include/evrpc.h /usr/include/evutil.h

FWIW even though CentOS 6 is a bit older, it is still in widespread use particularly at "conservative" installations.