[RFA] Add declaration in i386-tdep.h (for interix)

[Joel Brobecker]

> (The function would at least need to be namespace proofed - leading 
> i386_ bit I 386 question)

Ok, I'll wait for an i386 maintainer to comment. I can make this kind of
change, and I think it would make sense.

> BTW, Have you looked at the osabi mechanism?   The above may not even be 
> needed.

Yes, I am using this mechanism in the interix port to set the gdbarch
bits. That's where I need this definition, to get rid of one extern.

-- 
Joel