pterm now uses the new uxsel module, so it's one step closer to

being able to be a PuTTY as well as a pterm. In the process I've
also moved icky things like actually reading from the pty fd and
printing the `terminated on signal' messages into pty.c where they
obviously should have been in the first place. Also there's been one
interesting repercussion in the terminal code: terminal.c's
from_backend now calls term_out() directly rather than expecting the
front end to call it afterwards. This has had the entertaining side
effect of fixing a Windows-specific bug whereby activity in a port
forwarding through a PuTTY with a blinking cursor caused the cursor
to blink to ON (!!!!). So, a surprisingly far-reaching checkin as it
turns out...

[originally from svn r3017]

terminal.h

@@ -198,6 +198,16 @@ struct terminal_tag {
      * than only the default.
      */
     Config cfg;
+
+    /*
+     * from_backend calls term_out, but it can also be called from
+     * the ldisc if the ldisc is called _within_ term_out. So we
+     * have to guard against re-entrancy - if from_backend is
+     * called recursively like this, it will simply add data to the
+     * end of the buffer term_out is in the process of working
+     * through.
+     */
+    int in_term_out;
 };
 
 #define in_utf(term) ((term)->utf || (term)->ucsdata->line_codepage==CP_UTF8)