PCI extended configuration support

[Masanobu SAITOH]

 Hi, all.

 nonaka@ wrote code to access PCI extended configuration area.
Currently, the diff supoorts only on x86.

        
http://ftp.netbsd.org/pub/NetBSD/misc/nonaka/tmp/nbsd-pci-extconf-support.diff

Is it OK to commit?

-- 
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                SAITOH Masanobu (msai...@execsw.org
                                 msai...@netbsd.org)