Tidy up Object Access hooks tests

per gripelet from Tom Lane.

src/test/modules/test_oat_hooks/Makefile

@@ -1,13 +1,10 @@
 # src/test/modules/test_oat_hooks/Makefile
 
 MODULE_big = test_oat_hooks
-OBJS = \
-	$(WIN32RES) \
-	test_oat_hooks.o
+OBJS = test_oat_hooks.o $(WIN32RES)
 PGFILEDESC = "test_oat_hooks - example use of object access hooks"
 
 REGRESS = test_oat_hooks
-NO_INSTALLCHECK = 1
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config

src/test/modules/test_oat_hooks/expected/test_oat_hooks.out

@@ -155,7 +155,7 @@ NOTICE:  in process utility: superuser attempting set
 NOTICE:  in object_access_hook_str: superuser attempting alter (set) [test_oat_hooks.deny_utility_commands]
 NOTICE:  in object_access_hook_str: superuser finished alter (set) [test_oat_hooks.deny_utility_commands]
 NOTICE:  in process utility: superuser finished set
--- Try again as non-superuser with permisisons denied
+-- Try again as non-superuser with permissions denied
 SET SESSION AUTHORIZATION regress_test_user;
 NOTICE:  in process utility: superuser attempting set
 NOTICE:  in object_access_hook_str: non-superuser attempting alter (set) [session_authorization]

src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql

@@ -39,7 +39,7 @@ SET test_oat_hooks.deny_object_access = true;
 SET test_oat_hooks.deny_exec_perms = true;
 SET test_oat_hooks.deny_utility_commands = true;
 
--- Try again as non-superuser with permisisons denied
+-- Try again as non-superuser with permissions denied
 SET SESSION AUTHORIZATION regress_test_user;
 SELECT * FROM regress_test_table;
 SELECT regress_test_func('arg');

src/test/modules/test_oat_hooks/test_oat_hooks.c

@@ -192,6 +192,11 @@ _PG_fini(void)
 static void
 emit_audit_message(const char *type, const char *hook, char *action, char *objName)
 {
+	/*
+	 * Ensure that audit messages are not duplicated by only emitting them from
+	 * a leader process, not a worker process. This makes the test results
+	 * deterministic even if run with force_parallel_mode = regress.
+	 */
 	if (REGRESS_audit && !IsParallelWorker())
 	{
 		const char *who = superuser_arg(GetUserId()) ? "superuser" : "non-superuser";