patch 8.1.1458: crash when using gtags

Problem:    Crash when using gtags. (issue #4102)
Solution:   Check for negative row or col in screen_puts_len(). (Christian
            Brabandt)
diff --git a/src/screen.c b/src/screen.c
index 37999bb..53343e8 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -7707,7 +7707,11 @@
     int		force_redraw_next = FALSE;
     int		need_redraw;
 
-    if (ScreenLines == NULL || row >= screen_Rows)	/* safety check */
+    // Safety check. The check for negative row and column is to fix issue
+    // #4102. TODO: find out why row/col could be negative.
+    if (ScreenLines == NULL
+	    || row >= screen_Rows || row < 0
+	    || col >= screen_Columns || col < 0)
 	return;
     off = LineOffset[row] + col;