patch 8.2.0516: client-server code is spread out

Problem:    Client-server code is spread out.
Solution:   Move client-server code to a new file. (Yegappan Lakshmanan,
            closes #5885)

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    516,
 /**/
     515,
 /**/