* child_info.h (child_info::sync): Pass pid and HANDLE rather than using pinfo.

* child_info.h (child_info::sync): Pass pid and HANDLE rather than using pinfo.
(child_info::child_info): Accept an argument controlling whether to create
proc_subproc.
(child_info_spawn::child_info_spawn): Ditto.
* sigproc.cc (child_info::child_info): Ditto.
(child_info_spawn::child_info_spawn): Ditto.
(child_info::sync): Use passed in pid and HANDLE.
* fork.cc (fork_parent): Reflect additional arguments required for
child_info::sync.
* hookapi.cc (hook_or_detect_cygwin): Rename.  Change so that NULL 'fn'
argument just returns "true", indicating that program uses cygwin1.dll.
* spawn.cc (av::win16_exe): New element.
* spawn.cc (av::iscygwin): New element.
(av::fixup): New function.
(spawn_guts): Protect against SEGV.  Use fixup function to detect when it is
safe to wait for a spawned (as opposed to an execed) program.  Reflect changes
in child_info::sync arguments.
* external.cc (cygwin_internal): Reflect function renaming to
hook_or_detect_cygwin.
* cygheap.cc (cygheap_fixup_in_child): Close handle after debug fixup has been
done to prevent false positives in handle collision.
* exceptions.cc (try_to_debug): Notify debugger if already being debugged.