patch 8.1.1916: trying to allocate negative amount of memory closing popup

Problem:    Trying to allocate negative amount of memory when closing a popup.
Solution:   Check the rows are not out of bounds.  Don't finish a selection if
            it was never started.

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1916,
 /**/
     1915,
 /**/