Add "default_account" as a LUA job submit plugin variable.

This is useful in a submit plugin script that needs to do
different things depending on the account, as the the setting
of account from default account does not happen until after
the script has run.

src/plugins/job_submit/lua/job_submit_lua.c

@@ -243,6 +243,21 @@ static void _register_lua_slurm_output_functions (void)
 	lua_setglobal (L, "slurm");
 }
 
+/* Get the default account for a user (or NULL if not present) */
+static char *_get_default_account(uint32_t user_id)
+{
+	slurmdb_user_rec_t user;
+
+	memset(&user, 0, sizeof(slurmdb_user_rec_t));
+	user.uid = user_id;
+	if (assoc_mgr_fill_in_user(acct_db_conn,
+				   &user, 0, NULL) != SLURM_ERROR) {
+		return user.default_acct;
+	} else {
+		return NULL;
+	}
+}
+
 /* Get fields in an existing slurmctld job record
  * NOTE: This is an incomplete list of job record fields.
  * Add more as needed and send patches to slurm-dev@llnl.gov */
@@ -335,6 +350,8 @@ static int _get_job_req_field (lua_State *L)
 		lua_pushnumber (L, job_desc->contiguous);
 	} else if (!strcmp(name, "cores_per_socket")) {
 		lua_pushnumber (L, job_desc->cores_per_socket);
+	} else if (!strcmp(name, "default_account")) {
+		lua_pushstring (L, _get_default_account(job_desc->user_id));
 	} else if (!strcmp(name, "dependency")) {
 		lua_pushstring (L, job_desc->dependency);
 	} else if (!strcmp(name, "end_time")) {