* win32-low.c (soft_interrupt_requested, faked_breakpoint): New
global variables.
(child_add_thread): Minor cleanup.
(child_continue): Resume artificially suspended threads before
calling ContinueDebugEvent.
(suspend_one_thread): New.
(fake_breakpoint_event): New.
(get_child_debug_event): Change return type to int. Check here if
gdb sent an interrupt request. If a soft interrupt was requested,
fake a breakpoint event. Return 0 if there is no event to handle,
and 1 otherwise.
(win32_wait): Don't check here if gdb sent an interrupt request.
Ensure there is a valid event to handle.
(win32_request_interrupt): Add soft interruption method as last
resort.