* win32-nat.c (thread_rec): Be more defensive about suspending already

* win32-nat.c (thread_rec): Be more defensive about suspending already
suspended threads.
(safe_symbol_file_add_stub): New function.
(safe_symbole_file_add_cleanup): New function.
(safe_symbol_file_add): New function.
(handle_load_dll): Use wrapper to add DLL symbol information to avoid bogus
errors from non-stabs DLLs.
(handle_exception): Add work around for detection of first exception breakpoint
which does not seem to occur on W2K.  Detect more "signals" that can be
effectively passed to the debuggee.  Reorganize to eliminate continue_status
global.
(child_continue): Reorganize to eliminate continue_status global.
(child_wait): Ditto.
(child_resume): Ditto.
(get_child_debug_event): Ditto.  Recognize when an a breakpoint exception
should be ignored.  Change method for signalling when an important event has
occured to the caller.
(child_create_inferior): Use new method for noticing when get_child_debug_event
has found something interesting.