patch 9.0.0678: using exclamation marks on :function

Problem:    Using exclamation marks on :function.
Solution:   Use :func and :endfunc as usual.

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    678,
 /**/
     677,
 /**/