iv_time_posix: Use CLOCK_MONOTONIC_FAST if available.

Since CLOCK_MONOTONIC is excruciatingly slow on FreeBSD, and while
CLOCK_MONOTONIC_FAST is faster but less precise, we don't need the
extra precision for iv_now as much as we need the extra speed.

Suggestion from Balazs Scheidler <bazsi@balabit.hu>.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
iv_fd_poll: Remove superfluous sys/poll.h include.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
iv_main: Remove superfluous initializations to zero.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Include all files required for building in the tarball.

A couple of private, no-inst headers and the versioning linker scripts
are needed to build ivykis, so include them all in the tarball.

Reported-by: Peter Czanik <czanik@balabit.hu>
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>