* exceptions.cc: (ctrl_c_handler): Do nothing while a Cygwin subprocess is

* exceptions.cc: (ctrl_c_handler): Do nothing while a Cygwin subprocess is
starting.
* child_info.h (init_child_info): Remove pid argument from declaration.
* cygheap.h (init_cygheap::pid): New element.
* dcrt0.cc (dll_crt0_0): Eliminate handling of now-noexistent cygpid parameter
in child_info struct.  Set forkee to 'true' rather than cygpid since the pid
value was never used.
(dll_crt0_1): Ditto.
(_dll_crt0): Ditto.
* fork.cc (fork_child): Don't wait for sigthread.  This is handled in the fork
call now.
(fork_parent): Remove obsolete pid argument from init_child_info call.  Don't
do anything special with cygpid when DEBUGGING.
(fork): Delay all signals during fork.
(fork_init): Don't do anything special when DEBUGGING.
* pinfo.cc (set_myself): Remove pid parameter.  Use new pid field in cygheap.
(pinfo_init): Don't pass pid argument to set_myself.
* sigproc.cc (sig_send): Wait for dwProcessId to be non-zero as well as
sendsig.
(init_child_info): Eliminate handling of pid.
(wait_sig): Implement method to temporarily hold off sending signals.
* sigproc.h (__SIGHOLD): New enum.
(__SIGNOHOLD): Ditto.
* spawn.cc (spawn_guts): Remove obsolete pid argument from init_child_info
call.