(init_ops): Don't initialize ops.prepare_to_store.
	(store_regs_kern): Pre-fetch register buffers from child,
	because some registers may not be in the cache.  Copy
	regs from register cache only if they are cached.
	(store_regs_lib): Copy regs from register cache only
	if they are cached.
	(fill_sprs32, (fill_sprs64, fill_fprs, fill_gprs32,
	fill_gprs64): Ditto.