patch 8.1.0016: possible crash in term_wait()

Problem:    Possible crash in term_wait(). (Dominique Pelle)
Solution:   Check for a valid buffer after ui_delay(). (closes #2944)

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    16,
 /**/
     15,
 /**/