patch 8.1.0954: arguments of semsg() and siemsg() are not checked

Problem:    Arguments of semsg() and siemsg() are not checked.
Solution:   Add function prototype with __attribute__.
diff --git a/src/version.c b/src/version.c
index a266ce0..6fe4c9e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    954,
+/**/
     953,
 /**/
     952,