Auto-load safe-path and auto-load scripts-directory on Windows

[Eli Zaretskii]

> Date: Sat, 29 Aug 2015 13:24:36 +0200
> From: Jan Kratochvil <jan.kratochvil@redhat.com>
> Cc: gdb@sourceware.org
> 
> On Sat, 29 Aug 2015 10:55:34 +0200, Eli Zaretskii wrote:
> > I've noticed that the default values of these 2 path lists use ':' as
> > directory separator, even on MS-Windows.  Isn't that a bug?
> 
> Yes, that seems a bug to me.  I have no idea if configure is used for Mingw

It is, of course.  There's no other practical way of building GDB with
MinGW.

> and I guess ':' works for Cygwin.  So I still do not see how to fix that.

Using a variable set from the host, instead of a literal colon, seems
like a starting point, no?

> Besides that for example 'set debug-file-directory' originally allowed only
> one directory but for some years it allows a PATH-style list of directories.
> Should it be therefore the old option name deprecated + renamed?

Preferably the options should be called "directories" or "path", not
"directory".