Mount interaction with /dev & /proc entries

[Conrad Scott]

Before anyone else gets there, I'll reply to my own message (what a
change).

The patch I just sent for path.cc breaks (at least) find(1) on
/proc/registry -- it doesn't descend into it at all. Sorry.

So I've got something wrong in my understanding of the cygwin/win32
stuff (which doesn't surprise me). It still seems that something like
this change should be made. One difference betwen /proc and /dev is
that the /dev fs doesn't contain any directories. I'll go look some
more.

Cheers,

// Conrad