* bsd-kvm.c: Include "gdbthread.h".

	* bsd-kvm.c: Include "gdbthread.h".
	(bsd_kvm_ptid): New.
	(bsd_kvm_open): Add a main thread.
	(bsd_kvm_close): Delete it.
	(bsd_kvm_thread_alive): New.
	(bsd_kvm_pid_to_str): New.
	(bsd_kvm_add_target): Register bsd_kvm_thread_alive and
	bsd_kvm_pid_to_str.
	(bsd_kvm_add_target): Initialize bsd_kvm_ptid.