ich9->pic and ich9->ioapic differ for the first 16 GSIs (because
ich9->pic is wired to 8259+IOAPIC but ich9->ioapic is wired to
IOAPIC only). However, ich9->ioapic is never used for the first
16 GSIs, so the two vectors can be merged.
Reviewed-by: Efimov Vasily <real@ispras.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>