patch 8.0.0612: pack dirs are added to 'runtimepath' too late

Problem:    Package directories are added to 'runtimepath' only after loading
            non-package plugins.
Solution:   Split off the code to add package directories to 'runtimepath'.
            (Ingo Karkat, closes #1680)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    612,
 /**/
     611,
 /**/