patch 8.2.4942: error when setting 'filetype' in help file again

Problem:    Error when setting 'filetype' in help file again.
Solution:   Deal with text property type already existing. (closes #10409)
diff --git a/src/version.c b/src/version.c
index f34a322..480acfd 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4942,
+/**/
     4941,
 /**/
     4940,