Remove old host cases from toplevel configure

[Joseph S. Myers]

On Thu, 24 Mar 2011, Joseph S. Myers wrote:

> Furthermore, the whole idea of the toplevel configure tentative_cc
> setting code is dubious since this is an autoconf-generated script and
> it's autoconf's job to deal with finding a working compiler, putting
> it in ANSI C mode, etc. - so if someone did wish to resupport one of

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.

-- 
Joseph S. Myers
joseph@codesourcery.com