Fix the osx build

ft/ft-ops.h

@@ -232,7 +232,7 @@ void toku_ft_maybe_delete (FT_HANDLE ft_h, DBT *k, TOKUTXN txn, bool oplsn_valid
 TXNID toku_ft_get_oldest_referenced_xid_estimate(FT_HANDLE ft_h);
 TXN_MANAGER toku_ft_get_txn_manager(FT_HANDLE ft_h);
 
-class txn_gc_info;
+struct txn_gc_info;
 void toku_ft_send_insert(FT_HANDLE ft_h, DBT *key, DBT *val, XIDS xids, enum ft_msg_type type, txn_gc_info *gc_info);
 void toku_ft_send_delete(FT_HANDLE ft_h, DBT *key, XIDS xids, txn_gc_info *gc_info);
 void toku_ft_send_commit_any(FT_HANDLE ft_h, DBT *key, XIDS xids, txn_gc_info *gc_info);

ft/rollback.h

@@ -165,7 +165,7 @@ struct rollback_log_node {
     BLOCKNUM           previous; 
     struct roll_entry *oldest_logentry;
     struct roll_entry *newest_logentry;
-    struct memarena    rollentry_arena;
+    memarena           rollentry_arena;
     size_t             rollentry_resident_bytecount; // How many bytes for the rollentries that are stored in main memory.
     PAIR               ct_pair;
 };