patch 9.0.0356: :echowindow sets the in_echowindow flag too early

Problem:    :echowindow sets the in_echowindow flag too early.
Solution:   Set in_echowindow only when outputting the text. (Yasuhiro
            Matsumoto, closes #11033)
diff --git a/src/version.c b/src/version.c
index 356ac77..f017ba1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    356,
+/**/
     355,
 /**/
     354,