Improve autovacuum logging for aggressive and anti-wraparound runs

A log message was being generated when log_min_duration is reached for
autovacuum on a given relation to indicate if it was an aggressive run,
and missed the point of mentioning if it is doing an anti-wrapround
run.  The log message generated is improved so as one, both or no extra
details are added depending on the option set.

Author: Sergei Kornilov
Reviewed-by: Masahiko Sawada, Michael Paquier
Discussion: https://postgr.es/m/11587951532155118@sas1-19a94364928d.qloud-c.yandex.net

src/backend/commands/vacuumlazy.c

@@ -374,10 +374,20 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params,
 			 * emitting individual parts of the message when not applicable.
 			 */
 			initStringInfo(&buf);
+			if (params->is_wraparound)
+			{
+				if (aggressive)
+					msgfmt = _("automatic aggressive vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
+				else
+					msgfmt = _("automatic vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
+			}
+			else
+			{
 				if (aggressive)
 					msgfmt = _("automatic aggressive vacuum of table \"%s.%s.%s\": index scans: %d\n");
 				else
 					msgfmt = _("automatic vacuum of table \"%s.%s.%s\": index scans: %d\n");
+			}
 			appendStringInfo(&buf, msgfmt,
 							 get_database_name(MyDatabaseId),
 							 get_namespace_name(RelationGetNamespace(onerel)),