Remove old host cases from toplevel configure

[Paolo Bonzini]

On 03/24/2011 08:49 PM, Joseph S. Myers wrote:
> Related to that point, I notice a piece of code starting "we might need to
> use some other shell than /bin/sh for running subshells" that tries to
> determine a shell on Windows hosts.  It's autoconf's job to find a
> suitable shell, so if this code is still relevant I think there's
> something missing in autoconf.

That code is dead because

   if test x${CONFIG_SHELL} = x ; then

will never be true.

Paolo