* infrun.c (wait_for_inferior): When switching from one thread to

    * infrun.c (wait_for_inferior): When switching from one thread to
        another, save infrun's state for the old thread and load infrun's
        previous state for the new thread.
        * thread.c (struct thread_info): Add new fields for thread specific
        state saved/restored in infrun.c.
        (add_thread): Initialize new fields.
        (load_infrun_state): New function.
        (save_infrun_state): New function.
        * thread.h (load_infrun_state): Provide external decl.
        (save_infrun_state): Likewise.

More single-stepping patches for lynx-6100.