configure: install in a sub-dir of --libdir and --docdir

In case the user specifies the LIBDIR with --libdir , or DOCDIR with
--docdir, install our support files in a sub-dir, so as not to mangle
existing (potentially system) files/dirs.

 #!/bin/sh

 # Needed for systems without gettext

 $* -xc -o /dev/null - > /dev/null 2>&1 << EOF

 #include <libintl.h>

 int main()

 {

 	gettext("");

 	return 0;

 }

 EOF

 if [ ! "$?" -eq "0"  ]; then

 	echo -DKBUILD_NO_NLS;

 fi