* configure.srv [s390x-*-linux*]: Set srv_regobj to include both

	* configure.srv [s390x-*-linux*]: Set srv_regobj to include both
	reg-s390.o and reg-s390x.o.

	* linux-low.c (new_inferior): New global variable.
	(linux_create_inferior, linux_attach): Set it.
	(linux_wait_for_process): Call the_low_target.arch_setup after the
	target has stopped for the first time.
	(initialize_low): Do not call the_low_target.arch_setup.

	* linux-s390-low.c (s390_get_pc): Support bi-arch operation.
	(s390_set_pc): Likewise.
	(s390_arch_setup): New function.
	(the_low_target): Use s390_arch_setup as arch_setup routine.

	* regcache.c (realloc_register_cache): New function.
	(set_register_cache): Call it for each existing regcache.