patch 8.0.0707: freeing wrong memory with certain autocommands

Problem:    Freeing wrong memory when manipulating buffers in autocommands.
            (James McCoy)
Solution:   Also set the w_s pointer if w_buffer was NULL.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    707,
 /**/
     706,
 /**/