e0ed8ed664 went too far and broke the
backward compat headers for Linux systems.

This also removes the need for __weak_alias shims

implementation when it's not found. SO_TIMESTAMP was added in CVS rev 1.85
by henning@.

do not have it, and a getifaddrs substitute for Solaris 10.

Thanks to pbhenson for noticing this.

There are crypto hash function symbol overlaps between libmd and libcrypto on
FreeBSD, which causes hashing of the certificates store to fail as a
side-effect when using TLS constraints. Since all we really need is MD5, just
use the embedded OpenBSD versions instead.

This is used to ensure that the time is written to the RTC when it is
synced. Problem noticed and patched by Christian Weisgerber.

Remove unneeded AC_SUBST's, call AC_DEFINE for default and user-specified
cases.
Thanks to naddy@ for reporting and suggesting the fixes.

from naddy@

While this still doesn't affect the behavior of the daemon, the
configuration option can at least be set to check the correct privsep
directory for permissions. Revisit in 5.8 as a possible extension to the
runtime check instead to remove the 'knob'.

I could not find a lot of precedence for this, because most time
daemons do not actually look at the value of olddelta. Account for
olddelta getting stuck at 1ms, and for a NULL value of delta being
treated as an error condition.

Document CA path option.

this is only necessary if constraints are enabled