ioemu: fix warnings in pass-through.h and pass-through.c

ioemu: fix warnings in pass-through.h and pass-through.c

This patch backports following changes of ioemu-remote to ioemu.
It fixs warning in tools/ioemu/hw/pass-through.h and
tools/ioemu/hw/pass-through.c.

commit 30f00a0284a5ee356de6f6095e52173f2234145b
Author: Ian Jackson <ian.jackson@eu.citrix.com>
Date:   Fri Jul 18 16:02:23 2008 +0100

    hw/pass-through.c: pt_unregister_regions returns void

    It only ever falls off the end, and its return value is not used
    by its one caller.

    Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
commit 439836900dad41f66234d2a14981aa2a90d4d346
Author: Ian Jackson <ian.jackson@eu.citrix.com>
Date:   Tue Jul 22 11:55:18 2008 +0100

    Add missing cast for printf of maddr

commit cf5b00e6b714eb5f900d55471d85956b09cb8fd9
Author: Ian Jackson <ian.jackson@eu.citrix.com>
Date:   Thu Jul 24 13:57:10 2008 +0100

    pass-through.h: Sprinkle some #ifdefs to cope with pciutils-dev
    versions

    Some versions of pciutils-dev contain #defines which others are
    lacking.
    To avoid spurious compiler warnings we add some #ifdefs.  *sigh*

    Signed-off-by: Yuji Shimada <shimada-yxb@necst.nec.co.jp>
Signed-off-by: Yuji Shimada <shimada-yxb@necst.nec.co.jp>