x86: Issue reset on triple faults (Jan Kiszka)

As discussed a few times on this list: A triple fault causes a system
reset on x86, and some guests make use of this (e.g. 386BSD). To keep
the chance of tracing unexpected resets, log them if CPU_LOG_RESET is
set.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6453 c046a42c-6fe2-441c-8c8c-71466251a162
