Track per-relation cumulative time spent in [auto]vacuum and [auto]analyze

This commit adds four fields to the statistics of relations, aggregating
the amount of time spent for each operation on a relation:
- total_vacuum_time, for manual vacuum.
- total_autovacuum_time, for vacuum done by the autovacuum daemon.
- total_analyze_time, for manual analyze.
- total_autoanalyze_time, for analyze done by the autovacuum daemon.

This gives users the option to derive the average time spent for these
operations with the help of the related "count" fields.

Bump catalog version (for the catalog changes) and PGSTAT_FILE_FORMAT_ID
(for the additions in PgStat_StatTabEntry).

Author: Sami Imseih
Reviewed-by: Bertrand Drouvot, Michael Paquier
Discussion: https://postgr.es/m/CAA5RZ0uVOGBYmPEeGF2d1B_67tgNjKx_bKDuL+oUftuoz+=Y1g@mail.gmail.com

src/backend/utils/adt/pgstatfuncs.c

@@ -106,6 +106,34 @@ PG_STAT_GET_RELENTRY_INT64(tuples_updated)
 /* pg_stat_get_vacuum_count */
 PG_STAT_GET_RELENTRY_INT64(vacuum_count)
 
+#define PG_STAT_GET_RELENTRY_FLOAT8(stat)						\
+Datum															\
+CppConcat(pg_stat_get_,stat)(PG_FUNCTION_ARGS)					\
+{																\
+	Oid			relid = PG_GETARG_OID(0);						\
+	double		result;											\
+	PgStat_StatTabEntry *tabentry;								\
+																\
+	if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)	\
+		result = 0;												\
+	else														\
+		result = (double) (tabentry->stat);						\
+																\
+	PG_RETURN_FLOAT8(result);									\
+}
+
+/* pg_stat_get_total_vacuum_time */
+PG_STAT_GET_RELENTRY_FLOAT8(total_vacuum_time)
+
+/* pg_stat_get_total_autovacuum_time */
+PG_STAT_GET_RELENTRY_FLOAT8(total_autovacuum_time)
+
+/* pg_stat_get_total_analyze_time */
+PG_STAT_GET_RELENTRY_FLOAT8(total_analyze_time)
+
+/* pg_stat_get_total_autoanalyze_time */
+PG_STAT_GET_RELENTRY_FLOAT8(total_autoanalyze_time)
+
 #define PG_STAT_GET_RELENTRY_TIMESTAMPTZ(stat)					\
 Datum															\
 CppConcat(pg_stat_get_,stat)(PG_FUNCTION_ARGS)					\