patch 8.1.0772: the sign_define_by_name() function is too long

Problem:    The sign_define_by_name() function is too long.
Solution:   Split it into smaller functions. (Yegappan Lakshmanan,
            closes #3819)
diff --git a/src/version.c b/src/version.c
index 1c76457..84d5831 100644
--- a/src/version.c
+++ b/src/version.c
@@ -792,6 +792,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    772,
+/**/
     771,
 /**/
     770,