[patch:rfc] Invalidate ``current_gdbarch'' when createing a new

[Andrew Cagney]

> FYI,
> 
> 2002-04-20  Andrew Cagney  <ac131313@redhat.com>
> 
>     * gdbarch.sh (gdbarch_update_p): Swap out the old architecture
>     before probing for a new one.  Detect errorenous gdbarch_init
>     functions.
>     * gdbarch.c: Regenerate.
> 
> 
> I've checked this in.  If there is a mysterious core dump in gdbarch.c, suspect this .....

And I'm finding mysterious core dumps on a PPC target :-(  I've hanked 
this patch for the moment.
More testing sigh,

Andrew