patch 8.0.0239: no CI with an address sanitizer

Problem:    The address sanitizer sometimes finds errors, but it needs to be
            run manually.
Solution:   Add an environment to Travis with clang and the address sanitizer.
            (Christian Brabandt)  Also include changes only on github.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    239,
 /**/
     238,
 /**/