Editorialize a bit on new ProcessUtility() API.

Choose a saner ordering of parameters (adding a new input param after
the output params seemed a bit random), update the function's header
comment to match reality (cmon folks, is this really that hard?),
get rid of useless and sloppily-defined distinction between
PROCESS_UTILITY_SUBCOMMAND and PROCESS_UTILITY_GENERATED.

src/backend/commands/extension.c

@@ -750,10 +750,10 @@ execute_sql_string(const char *sql, const char *filename)
 			{
 				ProcessUtility(stmt,
 							   sql,
+							   PROCESS_UTILITY_QUERY,
 							   NULL,
 							   dest,
-							   NULL,
-							   PROCESS_UTILITY_QUERY);
+							   NULL);
 			}
 
 			PopActiveSnapshot();

src/backend/commands/schemacmds.c

@@ -151,10 +151,10 @@ CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString)
 		/* do this step */
 		ProcessUtility(stmt,
 					   queryString,
+					   PROCESS_UTILITY_SUBCOMMAND,
 					   NULL,
 					   None_Receiver,
-					   NULL,
-					   PROCESS_UTILITY_SUBCOMMAND);
+					   NULL);
 		/* make sure later steps can see the object created here */
 		CommandCounterIncrement();
 	}

src/backend/commands/trigger.c

@@ -1014,7 +1014,8 @@ ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid)
 		/* ... and execute it */
 		ProcessUtility((Node *) atstmt,
 					   "(generated ALTER TABLE ADD FOREIGN KEY command)",
-					   NULL, None_Receiver, NULL, PROCESS_UTILITY_GENERATED);
+					   PROCESS_UTILITY_SUBCOMMAND, NULL,
+					   None_Receiver, NULL);
 
 		/* Remove the matched item from the list */
 		info_list = list_delete_ptr(info_list, info);