patch 8.1.0632: using sign group names is inefficient

Problem:    Using sign group names is inefficient.
Solution:   Store group names in a hash table and use a reference to them.
            Also remove unnecessary use of ":exe" from the tests.  (Yegappan
            Lakshmanan, closes #3715)

src/version.c

@@ -799,6 +799,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    632,
 /**/
     631,
 /**/