adding list of SQL specific header argument names which should be inherited

* lisp/ob-sql.el (org-babel-header-arg-names:sql): SQL specific header
  argument names which should be inherited.

lisp/ob-sql.el

@@ -50,6 +50,9 @@
 
 (defvar org-babel-default-header-args:sql '())
 
+(defvar org-babel-header-arg-names:sql
+  '(engine out-file))
+
 (defun org-babel-expand-body:sql (body params)
   "Expand BODY according to the values of PARAMS."
   (org-babel-sql-expand-vars