Revert "commit_delay" change; just add comment that we don't have

a microsecond specification.

src/backend/utils/misc/guc.c

@@ -2033,8 +2033,8 @@ static struct config_int ConfigureNamesInt[] =
 		{"commit_delay", PGC_USERSET, WAL_SETTINGS,
 			gettext_noop("Sets the delay in microseconds between transaction commit and "
 						 "flushing WAL to disk."),
-			NULL,
-			GUC_UNIT_MS
+			NULL
+			/* we have no microseconds designation, so can't supply units here */
 		},
 		&CommitDelay,
 		0, 0, 100000,