patch 8.0.0336: flags of :substitute not sufficiently tested

Problem:    Flags of :substitute not sufficiently tested.
Solution:   Test up to two letter flag combinations. (James McCoy, closes
            #1479)
diff --git a/src/version.c b/src/version.c
index ef1f9ad..df77e82 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    336,
+/**/
     335,
 /**/
     334,