patch 8.1.0324: off-by-one error in cmdidx check

Problem:    Off-by-one error in cmdidx check. (Coverity)
Solution:   Use ">=" instead of ">".
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index fc2b20e..d4cf6a2 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -12554,7 +12554,7 @@
     int
 is_loclist_cmd(int cmdidx)
 {
-    if (cmdidx < 0 || cmdidx > CMD_SIZE)
+    if (cmdidx < 0 || cmdidx >= CMD_SIZE)
 	return FALSE;
     return cmdnames[cmdidx].cmd_name[0] == 'l';
 }