ITS#8969 tweak mdb_page_split

Bump up number of keys for which we use fine-grained splitpoint search

external/db_drivers/liblmdb/mdb.c

@@ -9641,7 +9641,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
 			 * the split so the new page is emptier than the old page.
 			 * This yields better packing during sequential inserts.
 			 */
-			if (nkeys < 20 || nsize > pmax/16 || newindx >= nkeys) {
+			if (nkeys < 32 || nsize > pmax/16 || newindx >= nkeys) {
 				/* Find split point */
 				psize = 0;
 				if (newindx <= split_indx || newindx >= nkeys) {