Free the status_file variable when shutting down

Otherwise we'll leak the memory. This fixes nagios#610.

Patch-by: pmalek (on tracker.nagios.org)
Signed-off-by: Andreas Ericsson <ae@op5.se>
Print the error reason when synchronous fork() calls fail

We only use them for performance data handling, so it's rare
that they're ever used, but there's a bug for them in the
Nagios tracker which would've been a lot more helpful to read
if the error message had been included, so let's make it so.

Signed-off-by: Andreas Ericsson <ae@op5.se>
Revert "Use ck_assert_ptr_ne() instead of ck_assert(ptr != other_ptr)"

This reverts commit 0c799f19a7cbccb3e8d9eb90f35691c58c4be06e.

Because the travis box apparently doesn't support it, so the builds
fail with this patch included.

Signed-off-by: Andreas Ericsson <ae@op5.se>