Fix for PR threads/1048

Fix for PR threads/1048
* win32-nat.c (thread_info_struct): Add reload_context flag.
(thread_rec): Don't reload thread context here.  Just set a flag.
(do_child_fetch_inferior_registers): Reload thread context here if appropriate.
Avoid doing anything if current_thread is NULL thanks to strange Windows
behavior.
(child_fetch_inferior_registers): Avoid doing anything if current_thread is
NULL.
(do_child_store_inferior_registers): Ditto.
(child_store_inferior_registers): Ditto.
(child_kill_inferior): Ditto.
(fake_create_process): Pretend to create a process for pathological windows
attach situation.
(get_child_debug_event): Call fake_create_process when the first event noticed
is thread creation rather than process creation.
(child_attach): Always set attach_flag when attaching.
(child_create_inferior): Set attach_flag to zero since we're not attaching.