* DevNotes: Add entry cgf-000022.

* cygtls.h (_cygtls::func): Define as a sa_sigaction style function.
* exceptions.cc (sig_handle_tty_stop): Ditto.
(_cygtls::interrupt_setup): Fix coercion to accommodate 'func' change.
(ctrl_c_handler): Use tty kill_pgrp to send a signal.
(sigpacket::process): Don't process sigflush here.
(_cygtls::call_signal_handler): Reorganize to avoid a race.  Always call
sa_sigaction style function.
* fhandler_termios.cc (is_flush_sig): Define new function.
(tty_min::kill_pgrp): Handle tty flush when signal detected.
(fhandler_termios::bg_check): Be slightly more paranoid about checking for
valid tty.
(fhandler_termios::sigflush): Don't flush unless tty owner.
* fhandler_tty.cc (fhandler_pty_slave::ioctl): Use tty kill_pgrp to send
signal.
(fhandler_pty_master::ioctl): Ditto.
* signal.cc (killsys): Delete definition.
* sigproc.h (killsys): Delete declaration.
* include/cygwin/signal.h (siginfo_t): Simplify union/struct nesting slightly.
Implement mechanism to allow cygwin data passing.

winsup/cygwin/DevNotes

@@ -1,3 +1,18 @@
+2013-01-31  cgf-000022
+
+While researching the lftp behavior reported here:
+
+http://cygwin.com/ml/cygwin/2013-01/msg00390.html
+
+after a frenzy of rewriting sigflush handling to avoid blocking in the
+signal thread (which is now and should ever have been illegal), it
+dawned on me that we're not supposed to be flushing the tty input buffer
+every time a signal is received.  We're supposed to do this only when
+the user hits a character (e.g., CTRL-C) which initiates a signal
+action.  So, I removed sigflush from sigpacket::process and moved it to
+tc ()->kill_pgrp ().  This function should only be called to send
+signals related to the tty so this should have the desired effect.
+
 2013-01-11  cgf-000021
 
 Apparently I got the signal handling semantics of select() wrong again