configure.ac (target_header_dir): Move block defining this to before the block setting inhibit_libc.

	* configure.ac (target_header_dir): Move block defining
	this to before the block setting inhibit_libc.
	(inhibit_libc): When considering $with_headers, just
	check it it's explicitly "no".  If not, also check if
	$target_header_dir/stdio.h is present.  If not, set
	inhibit_libc=true.
	* configure: Regenerate.

From-SVN: r215439