patch 8.2.2352: if focus lost/gained is received twice code is not ignored

Problem:    If the focus lost/gained escape sequence is received twice it is
            not ignored. (Christ van Willigen)
Solution:   Adjust the logic to ignore the escape code.
diff --git a/src/version.c b/src/version.c
index b2de011..acca7aa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2352,
+/**/
     2351,
 /**/
     2350,