patch 8.1.0623: iterating through window frames is repeated

Problem:    Iterating through window frames is repeated.
Solution:   Define FOR_ALL_FRAMES. (Yegappan Lakshmanan)

src/version.c

@@ -799,6 +799,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    623,
 /**/
     622,
 /**/