pgstattuple: Use double consistently for percentages

pgstattuple uses data type double for other percentage calculations
and exposes those values to the users via the float8 data type.
However, scanned_percent in struct output_type is of type uint64, even
though it is later returned via Float8GetDatum().  Change it to use
double to be inline with other percentages.

Author: Bharath Rupireddy
Reviewed-by: Peter Eisentraut
Discussion: https://www.postgresql.org/message-id/36ee692b-232f-0484-ce94-dc39d82021ad%40enterprisedb.com

Author: petere

contrib/pgstattuple/pgstatapprox.c

@@ -38,7 +38,7 @@ Datum		pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo);
 typedef struct output_type
 {
 	uint64		table_len;
-	uint64		scanned_percent;
+	double		scanned_percent;
 	uint64		tuple_count;
 	uint64		tuple_len;
 	double		tuple_percent;
@@ -203,7 +203,7 @@ statapprox_heap(Relation rel, output_type *stat)
 	 */
 	if (nblocks != 0)
 	{
-		stat->scanned_percent = 100 * scanned / nblocks;
+		stat->scanned_percent = 100.0 * scanned / nblocks;
 		stat->tuple_percent = 100.0 * stat->tuple_len / stat->table_len;
 		stat->dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len;
 		stat->free_percent = 100.0 * stat->free_space / stat->table_len;