ctx->nx only got ORed, but never reset. So when one page in the
lifetime of the VM was ever NX, all later pages were too.

Signed-off-by: Alexander Graf <alex@csgraf.de>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6755 c046a42c-6fe2-441c-8c8c-71466251a162