Only engage a GTK idle function when absolutely necessary, otherwise

the whole app spins on it and takes up CPU all the time.

[originally from svn r2052]

terminal.c

@@ -3708,6 +3708,11 @@ void term_nopaste()
     paste_len = 0;
 }
 
+int term_paste_pending(void)
+{
+    return paste_len != 0;
+}
+
 void term_paste()
 {
     static long last_paste = 0;