tests: avoid xend ABRT crash report

tests: avoid xend ABRT crash report

I installed the xen development packages on my non-Xen F16 machine
in order to compile-test xen code and ensure we don't break things
on that front, but being a non-xen machine, /usr/sbin/xend is
obviously not running.  Unfortunately, xen-4.1.2-1.fc16 has a bug
where merely trying to probe xend status on a non-xen kernel causes
xend to issue an ABRT crash report:

https://bugzilla.redhat.com/show_bug.cgi?id=728696

Even though libvirt (correctly) skips the test, the xend crash report
is unnecessary noise.  Fix this by first filtering out non-xen
kernels even before attempting to probe xend.  The test still runs
and passes on a RHEL 5 xen kernel after this patch.

* tests/reconnect.c (mymain): Skip xend probe on non-xen kernel.
* tests/statstest.c (mymain): Likewise.