patch 7.4.1840

Problem:    When using packages an "after" directory cannot be used.
Solution:   Add the "after" directory of the package to 'runtimepath' if it
            exists.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1840,
 /**/
     1839,
 /**/