2011-12-20 Pedro Alves <alves.ped@gmail.com>

2011-12-20  Pedro Alves  <alves.ped@gmail.com>
	    Jan Kratochvil  <jan.kratochvil@redhat.com>

        * linux-nat.c (add_lwp): Don't call linux_nat_new_thread on the
	first LWP.
	* amd64-linux-nat.c (update_debug_registers_callback): Instantiate
	`lwp->arch_private' if NULL.
	(amd64_linux_prepare_to_resume): Do nothing if `lwp->arch_private'
	is NULL.
	* i386-linux-nat.c (update_debug_registers_callback): Instantiate
	`lwp->arch_private' if NULL.
	(i386_linux_prepare_to_resume): Do nothing if `lwp->arch_private'
	is NULL.