Treat SIGINT correctly in GUI sessions on MS-Windows

* src/w32proc.c (sys_signal): Don't reject SIGINT, as it is
supported by MS runtime.
* src/term.c (DEV_TTY): Move from here ...
* src/conf_post.h (DEV_TTY): ... to here.  Separate definitions
for WINDOWSNT and for the rest.
* src/keyboard.c (handle_interrupt_signal): Use DEV_TTY instead of
a literal "/dev/tty".

* etc/NEWS: Mention the behavior change.

1 files changed, 7 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 3092e9f22b9..79a476ca665 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -607,6 +607,13 @@ still apply.)
 Previously, on MS-Windows this function converted slash characters in
 file names into backslashes.  It no longer does that.
 
+** GUI sessions now treat SIGINT like Posix platforms do.
+The effect of delivering a Ctrl-C (SIGINT) signal to a GUI Emacs on
+MS-Windows is now the same as on Posix platforms -- Emacs saves the
+session and exits.  In particular, this will happen if you start
+emacs.exe from the Windows shell, then type Ctrl-C into that shell's
+window.
+
 
 * Installation Changes in Emacs 25.1