Bug 403552 s390x: Fix vector facility bit number

Bug 403552 s390x: Fix vector facility bit number

The wrong bit number was used when checking for the vector facility.  This
can result in a fatal emulation error: "Encountered an instruction that
requires the vector facility.  That facility is not available on this
host."

In many cases the wrong facility bit was usually set as well, hence
nothing bad happened.  But when running Valgrind within a Qemu/KVM guest,
the wrong bit was not (always?) set and the emulation error occurred.

This fix simply corrects the vector facility bit number, changing it from
128 to 129.