patch 9.0.0978: build errors without the +channel feature

Problem:    Build errors without the +channel feature. (John Marriott)
Solution:   Adjust #ifdefs.

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    978,
 /**/
     977,
 /**/