patch 9.0.1079: leaking memory when defining a user command fails

Problem:    Leaking memory when defining a user command fails.
Solution:   Free "compl_arg" when needed. (closes #11726)
diff --git a/src/version.c b/src/version.c
index 1ce4042..401d78b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1079,
+/**/
     1078,
 /**/
     1077,