* exception.h (cygwin_exception): New class.
(cygwin_exception::dumpstack): Declare new function.
(cygwin_exception::context): Ditto.
(cygwin_exception::dump_exception): Ditto.
* exceptions.cc (cygwin_exception::dump_exception): Move into cygwin_exception
class. Accommodate new variable names.
(cygwin_exception::dumpstack): Ditto stackdump -> dumpstack.
(exception::handle): Move andreas processing earlier. Defer signal processing
decisions to the signal thread where they belong. Pass exception information
to sig_send via new siginfo_t si_cyg field.
(ctrl_c_handler): Wait for SIGHUP signal to be processed since it could cause a
process exit and we don't want races with thread exit lock.
(signal_exit): Move back here from sigproc.cc. Modify arguments and remove
from sigpacket class. Decide when to dump core based on signal type.
(sigpacket::process): Handle exiting signals in context of threads rather than
in the signal thread. Signal debugger on non-Windows signals. Remove
setup_signal_exit call.
* sigproc.cc (no_signals_available): Remove argument.
(signal_exit_code): Delete.
(close_my_readsig): Ditto.
(_cygtls::signal_exit): Move to exceptions.cc.
(sigproc_terminate): Don't attempt to terminate signal thread.
(setup_signal_exit): Delete.
(exit_thread): Use new si_cyg entry in siginfo_t.
(sig_send): Just use empty initializer for si. Accommodate change in
no_signals_available argument.
(wait_sig): Remove attempt to "go asynchronous" on process exit. Delete
__SIGEXIT handling. Don't ever exit.
* sigproc.h: Remove __SIGEXIT from signal enum. Renumber.
* include/cygwin/signal.h (siginfo_t): Add si_cyg entry.