(inf_ptrace_open, inf_ptrace_reported_exec_events_per_call)
(inf_ptrace_can_run, inf_ptrace_post_attach): Removed.
(inf_ptrace_target): Don't set to_open,
to_reported_exec_events_per_call, to_can_run, to_post_attach,
to_stratum, to_has_all_memory, to_has_memory, to_has_stack,
to_has_registers, to_has_execution, to_magic.  Reorder remaining
initializations.