pg_stat_statements: add missing check for pgss_enabled().

Make pgss_post_parse_analyze() more consistent with the other hooks,
and avoid unnecessary overhead when pg_stat_statements.track=none.

Author: Raymond Martin
Reviewed-by: Fabien COELHO
Discussion: https://postgr.es/m/BN8PR21MB1217B003C4F79DE230AA36B9B1580%40BN8PR21MB1217.namprd21.prod.outlook.com

contrib/pg_stat_statements/pg_stat_statements.c

@@ -788,7 +788,7 @@ pgss_post_parse_analyze(ParseState *pstate, Query *query)
 	Assert(query->queryId == UINT64CONST(0));
 
 	/* Safety check... */
-	if (!pgss || !pgss_hash)
+	if (!pgss || !pgss_hash || !pgss_enabled())
 		return;
 
 	/*