vt: provide notifications on selection changes

commit 19e3ae6b upstream.

The vcs device's poll/fasync support relies on the vt notifier to signal
changes to the screen content.  Notifier invocations were missing for
changes that comes through the selection interface though.  Fix that.

Tested with BRLTTY 5.2.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Cc: Dave Mielke <dave@mielke.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/tty/vt/vt.c

@@ -498,6 +498,7 @@ void invert_screen(struct vc_data *vc, int offset, int count, int viewed)
 #endif
 	if (DO_UPDATE(vc))
 		do_update_region(vc, (unsigned long) p, count);
+	notify_update(vc);
 }
 
 /* used by selection: complement pointer position */
@@ -514,6 +515,7 @@ void complement_pos(struct vc_data *vc, int offset)
 		scr_writew(old, screenpos(vc, old_offset, 1));
 		if (DO_UPDATE(vc))
 			vc->vc_sw->con_putc(vc, old, oldy, oldx);
+		notify_update(vc);
 	}
 
 	old_offset = offset;
@@ -531,8 +533,8 @@ void complement_pos(struct vc_data *vc, int offset)
 			oldy = (offset >> 1) / vc->vc_cols;
 			vc->vc_sw->con_putc(vc, new, oldy, oldx);
 		}
+		notify_update(vc);
 	}
-
 }
 
 static void insert_char(struct vc_data *vc, unsigned int nr)