Negative four byte displacements need to be sign-extended after
c086b783eb7a578993d6d2ab62c4c2666800b63d. Do so.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>