patch 8.1.1631: displaying signs is inefficient

Problem:    Displaying signs is inefficient.
Solution:   Avoid making multiple calls to get information about a placed
            sign. (Yegappan Lakshmanan, closes #4586)
diff --git a/src/version.c b/src/version.c
index 90f8e08..4759fd6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1631,
+/**/
     1630,
 /**/
     1629,