#257 Cygwin filesystem support enhancement

[Mumit Khan]

The current Cygwin support code in Tcl works well for
8.3.x, but the new
FS code made the following changes necessary. The patch
basically moves
around some of the existing Cygwin hacks, er support,
code; it also uses
Cygwin chdir instead of Windows to make sure the
internal state is
consistent when the user changes to a directory that is
Cygwin mountpoint,
not directly available from the underlying OS.

With the excellent new FS code, the only Cygwin
specific code should have
been in SetFsPathFromAny, but we also need to add the
same snippet to
support globbing without patterns (eg., ``glob
/home/foo'').

[Mumit Khan]

Patch against Tcl 8.4.1

[Jeffrey Hobbs]

Logged In: YES
user_id=72656

applied with offsets for 8.4.4 and 8.5a.