patch 8.1.0620: overuling CONF_ARGS from the environment no longer works

Problem:    Overuling CONF_ARGS from the environment no longer works. (Tony
            Mechelynck)
Solution:   Do not define any CONF_ARGS by default.
diff --git a/src/version.c b/src/version.c
index b1a28c1..333a98f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    620,
+/**/
     619,
 /**/
     618,