call it instead of doing normal loop.
* infcmd.c (attach_command): Don't call wait_for_inferior if
running Mach 3.
* infrun.c (proceed) [PREPARE_TO_PROCEED]: If defined, call
hook that can decide whether to step over the next breakpoint.
* utils.c (wrap_here): Abort if wrap_buffer not allocated.
(request_quit) [REQUEST_QUIT]: If defined, call it instead of
doing normal quit.
* Makefile.in (stop-gdb): New target.
* stop-gdb.c: New file, utility to get attention of waiting GDBs
in Mach 3.