patch 8.2.1832: readdirex() error is displayed as a message

Problem:    readdirex() error is displayed as a message. (Yegappan Lakshmanan)
Solution:   Use semsg() instead of smsg().
diff --git a/src/fileio.c b/src/fileio.c
index 83924b3..3d6ff0d 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4743,7 +4743,7 @@
     if (!ok)
     {
 	failed = TRUE;
-	smsg(_(e_notopen), path);
+	semsg(_(e_notopen), path);
     }
     else
     {
@@ -4813,7 +4813,7 @@
     if (dirp == NULL)
     {
 	failed = TRUE;
-	smsg(_(e_notopen), path);
+	semsg(_(e_notopen), path);
     }
     else
     {