window-port updates

Remove start_screen() and end_screen() from the
Window-port interface.

They were only ever used by tty, and there was a comment
carried to several window-ports about how they "really
should go away. They are tty-specific"

term_start_screen() and term_end_screen() are part of
terminal/NO_TERMS supporting routines now.

sys/windows/consoletty.c

@@ -1052,7 +1052,7 @@ void
 settty(const char *s)
 {
     cmov(ttyDisplay->curx, ttyDisplay->cury);
-    end_screen();
+    term_end_screen();
     if (s)
         raw_print(s);
     restore_original_console_font();
@@ -1075,7 +1075,7 @@ settty(const char *s)
 void
 setftty(void)
 {
-    start_screen();
+    term_start_screen();
 }
 
 void
@@ -1113,7 +1113,7 @@ graph_off(void)
 #endif
 
 void
-tty_end_screen(void)
+term_end_screen(void)
 {
     term_clear_screen();
     really_move_cursor();
@@ -1123,7 +1123,7 @@ tty_end_screen(void)
 }
 
 void
-tty_start_screen(void)
+term_start_screen(void)
 {
     if (iflags.num_pad)
         tty_number_pad(1); /* make keypad send digits */

sys/windows/windsys.c

@@ -231,8 +231,10 @@ VA_DECL(const char *, s)
     VA_START(s);
     VA_INIT(s, const char *);
     /* error() may get called before tty is initialized */
+#ifdef TTY_GRAPHICS
     if (iflags.window_inited)
-        end_screen();
+        term_end_screen();
+#endif
     if (WINDOWPORT(tty)) {
         buf[0] = '\n';
         (void) vsnprintf(&buf[1], sizeof buf - (1 + sizeof "\n"), s, VA_ARGS);