INCLUDES are now deprecated and throw warnings when using automake 1.13.
We now also differentiate AM_CPPFLAGS and AM_CFLAGS, where includes and
defines are passed to AM_CPPFLAGS only.
The system time can be periodically checked. If it gets valid, certificates get
rechecked with the current lifetime. If certificates are invalid, associated
IKE_SAs can be closed or reauthenticated.