patch 8.0.1797: terminal window is redrawn too often

Problem:    Terminal window is redrawn too often and scrolling is repeated.
Solution:   Don't scroll immediately but only when redrawing.  Avoid redrawing
            the whole terminal window on every change.
diff --git a/src/proto/terminal.pro b/src/proto/terminal.pro
index 78b640f..f97f025 100644
--- a/src/proto/terminal.pro
+++ b/src/proto/terminal.pro
@@ -14,12 +14,13 @@
 int send_keys_to_term(term_T *term, int c, int typed);
 int terminal_is_active(void);
 cursorentry_T *term_get_cursor_shape(guicolor_T *fg, guicolor_T *bg);
-void term_win_entered(void);
 int term_use_loop(void);
+void term_win_entered(void);
 int terminal_loop(int blocking);
 void term_job_ended(job_T *job);
 void term_channel_closed(channel_T *ch);
-int term_update_window(win_T *wp);
+int term_do_update_window(win_T *wp);
+void term_update_window(win_T *wp);
 int term_is_finished(buf_T *buf);
 int term_show_buffer(buf_T *buf);
 void term_change_in_curbuf(void);