bad include search order in top level configure.in

[Jan Beulich]

In a patch submitted under "Re: Bugs in sysroot patches resulting in
$(local_include)/include always searched, ../-expansion broken",
searching of $(build_tooldir)/sys-include was added to FLAGS_FOR_TARGET.
However, the order specified here (include preceeding sys-include)
contradicts that used (almost) anywhere else (include following
sys-include), leading to problems (e.g. when building libstdc++ during a
cross compiler build) if identically named headers exist in both
sys-include and include. Unless there was a specific reason for this
ordering I'd like to request reversing it.

Thanks, Jan