exit() will call atexit handlers, which may try to
clean up things or wait for things to get cleaned up,
which we don't want or need. We just want to stop
and let the parent know about the failure as quickly
as possible in case fork() is used.
Fixes timeouts on assert failures in checks where
an exit handler waits for things to stop, but they
don't stop because they haven't been shut down,
and they haven't been shut down because there's no
simple way to do so on failures.
http://sourceforge.net/p/check/patches/50/
Include unistd.h so that _POSIX_VERSION is actually defined when
it should be defined. Without that, stuff like fail_if(1) doesn't
actually fail, presumably because other parts of the code do include
unistd.h and then have _POSIX_VERSION defined.
Fixes#604565 even more.
