patch 9.1.1456: comment plugin fails toggling if 'cms' contains \

Problem:  comment plugin fails toggling if 'cms' contains \
Solution: escape backslash (Maxim Kim)

groff could be commented using \" or \# and comment plugin fails to
uncomment such things.

NOTE: if newstyle comment would be introduced, e.g. .\#
for groff test would need to be adjusted.

closes: #17530

Signed-off-by: Maxim Kim <habamax@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 69cf433..a7b31ca 100644
--- a/src/version.c
+++ b/src/version.c
@@ -710,6 +710,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1456,
+/**/
     1455,
 /**/
     1454,