patch 8.1.0623: iterating through window frames is repeated

Problem:    Iterating through window frames is repeated.
Solution:   Define FOR_ALL_FRAMES. (Yegappan Lakshmanan)
diff --git a/src/version.c b/src/version.c
index bb0c81f..f57ffb3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    623,
+/**/
     622,
 /**/
     621,