[RFA] Fix remote-fileio.c compilation for Cygwin 1.5 API

[Pierre Muller]

> >> I do not really know if there is a specific maintainer for this
> >> file... Could someone (a global maintainr?)
> >> please review this patch?
> >
> >This is OK.
> 
> Sorry, I guess I was wrong about the opinion.  I do have a mild one.
> 
> While I said I didn't have an opinion about this, wouldn't it really
> make sense to use the same mechanism that I adopted for windows-nat.c?

The problem is that this macro does not check the value of the first
argument, which makes me fear that if someone reuses
cygwin_conv_path function elsewhere inside remote-fileio.c source
we might get into the same troubles as the ones
I just discovered for windows-nat.c

See http://sourceware.org/ml/gdb-patches/2010-03/msg00344.html

Pierre