monitor: fix build breakage for !CONFIG_VNC Commit c62f6d1 (monitor: fix build breakage with --disable-vnc) conditionalised some VNC setup code but left an unused variable. Move the variable into the conditional code to fix the build breakage. Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Signed-off-by: Jamie Iles <jamie@jamieiles.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>