set up.
(break_here): New function, for debugging.
(initial_env): Add program name to "Sleeping" message. Implement new
"CYGWIN_DEBUG" environment variable option.
* exceptions.cc (debugger_command): Add argument to dumper call.
* strace.cc (strace::hello): Use winpid if cygwin pid is unavailable.
(strace::vsprntf): Ditto.