(rs6000-*-aix*): New target; use aixrs6.
* emulparams/aixppc.sh, emulparams/aixrs6.sh: New files.
* emultempl/aix.em: New file.
* scripttempl/aix.sc: New file.
* Makefile.in (ALL_EMULATIONS): Add eaixppc.o and eaixrs6.o.
(eaixppc.c, eaixrs6.c): New targets.