Fix NM/AR propagation from toplevel for recursive makes.

* Makefile.in (AR): Use @AR@ not ar.
(NM): New.
(AR_FOR_TARGET): Use $(AR) not ar for native.
(NM_FOR_TARGET): Use $(NM) not nm for native.
* configure.ac: Add AC_CHECK_PROG calls for NM and AR.
* configure: Regenerate.

From-SVN: r84600