patch 9.1.0040: issue with prompt buffer and hidden buffer

Problem:  Modifying a hidden buffer still interferes with prompt buffer
          mode changes.
Solution: Save and restore b_prompt_insert.
          (zeertzjq)

closes: #13875

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
Modifying hidden buffer still interferes with prompt buffer mode changes
diff --git a/src/version.c b/src/version.c
index e3272f1..924c6f1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    40,
+/**/
     39,
 /**/
     38,