* archures.c, cpu-m68k.c, cpu-sparc.c: Undo 16 June changes.

* archures.c, cpu-m68k.c, cpu-sparc.c: Undo 16 June changes.
* libaout.h (struct aout_backend_data): New callback "set_sizes".
* aout-target.h (callback): Don't set page/seg sizes.
(mkobject): Ditto.
(set_sizes): New routine.
(backend_data): Point to it.
* aoutf1.h (sunos4_set_sizes): Heed architecture when setting sizes.
(sunos4_aout_backend): Point to it.
* aoutx.h (set_arch_mach): Call set_sizes callback.