[rfc] using --with-sysroot for native builds

[Alan Modra]

On Fri, Oct 29, 2010 at 10:59:34AM -0400, Daniel Jacobowitz wrote:
> On Fri, Oct 29, 2010 at 04:42:08PM +0200, Matthias Klose wrote:
> > the attached patch makes this change in ldmain.c conditionally on
> > native/cross.  An alternative would be to make the change
> > unconditionally and let the configure fail for a cross build, if
> > --with-sysroot is missing in the configure args, or if the value
> > passed is `' or `/'.
> 
> IMO, a cross linker should default to not using a sysroot, but still
> support the --sysroot option...

See genscripts.sh occurrences of use_sysroot.  As Andreas pointed out
we cannot start using native search paths for cross tools, but
--sysroot ought to use the native paths within the sysroot.
Supporting this isn't just a simple patch, is it?

-- 
Alan Modra
Australia Development Lab, IBM