ltcf-cxx.sh (ac_cv_prog_cc_pic_works, [...]): Don't unset, it's non-portable and no longer necessary, set to empty instead.

	* ltcf-cxx.sh (ac_cv_prog_cc_pic_works, ac_cv_prog_cc_static_works):
	Don't unset, it's non-portable and no longer necessary, set to empty
	instead.

From-SVN: r39300