patch 8.2.3159: cursor displayed in wrong position after deleting line

Problem:    Cursor displayed in wrong position after deleting line.
Solution:   When deleting lines do not approximate botline. (fixes #8559)
diff --git a/src/change.c b/src/change.c
index 248e6d8..73ea64f 100644
--- a/src/change.c
+++ b/src/change.c
@@ -563,9 +563,12 @@
 		changed_cline_bef_curs_win(wp);
 	    if (wp->w_botline >= lnum)
 	    {
-		// Assume that botline doesn't change (inserted lines make
-		// other lines scroll down below botline).
-		approximate_botline_win(wp);
+		if (xtra < 0)
+		    invalidate_botline_win(wp);
+		else
+		    // Assume that botline doesn't change (inserted lines make
+		    // other lines scroll down below botline).
+		    approximate_botline_win(wp);
 	    }
 
 	    // Check if any w_lines[] entries have become invalid.