patch 9.0.0299: error messages for setcmdline() could be better

Problem:    Error messages for setcmdline() could be better.
Solution:   Use more specific error messages. (Yegappan Lakshmanan,
            closes #10995)
diff --git a/src/version.c b/src/version.c
index 69cfafe..1af4b7d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    299,
+/**/
     298,
 /**/
     297,