blockchain_db: allow getting output keys without commitment

Since the commitment has to be calculated for non rct outputs,
it slows down a lot unnecessarily if we don't need it

src/blockchain_db/blockchain_db.h

@@ -1258,7 +1258,7 @@ public:
    *
    * @return the requested output data
    */
-  virtual output_data_t get_output_key(const uint64_t& amount, const uint64_t& index) const = 0;
+  virtual output_data_t get_output_key(const uint64_t& amount, const uint64_t& index, bool include_commitmemt = true) const = 0;
 
   /**
    * @brief gets an output's tx hash and index

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -2536,7 +2536,7 @@ uint64_t BlockchainLMDB::get_num_outputs(const uint64_t& amount) const
   return num_elems;
 }
 
-output_data_t BlockchainLMDB::get_output_key(const uint64_t& amount, const uint64_t& index) const
+output_data_t BlockchainLMDB::get_output_key(const uint64_t& amount, const uint64_t& index, bool include_commitmemt) const
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
   check_open();
@@ -2563,7 +2563,8 @@ output_data_t BlockchainLMDB::get_output_key(const uint64_t& amount, const uint6
   {
     const pre_rct_outkey *okp = (const pre_rct_outkey *)v.mv_data;
     memcpy(&ret, &okp->data, sizeof(pre_rct_output_data_t));;
-    ret.commitment = rct::zeroCommit(amount);
+    if (include_commitmemt)
+      ret.commitment = rct::zeroCommit(amount);
   }
   TXN_POSTFIX_RDONLY();
   return ret;

src/blockchain_db/lmdb/db_lmdb.h

@@ -242,7 +242,7 @@ public:
 
   virtual uint64_t get_num_outputs(const uint64_t& amount) const;
 
-  virtual output_data_t get_output_key(const uint64_t& amount, const uint64_t& index) const;
+  virtual output_data_t get_output_key(const uint64_t& amount, const uint64_t& index, bool include_commitmemt) const;
   virtual void get_output_key(const epee::span<const uint64_t> &amounts, const std::vector<uint64_t> &offsets, std::vector<output_data_t> &outputs, bool allow_partial = false) const;
 
   virtual tx_out_index get_output_tx_and_index_from_global(const uint64_t& index) const;

tests/unit_tests/testdb.h

@@ -89,7 +89,7 @@ public:
   virtual uint64_t get_tx_block_height(const crypto::hash& h) const { return 0; }
   virtual uint64_t get_num_outputs(const uint64_t& amount) const { return 1; }
   virtual uint64_t get_indexing_base() const { return 0; }
-  virtual cryptonote::output_data_t get_output_key(const uint64_t& amount, const uint64_t& index) const { return cryptonote::output_data_t(); }
+  virtual cryptonote::output_data_t get_output_key(const uint64_t& amount, const uint64_t& index, bool include_commitmemt) const { return cryptonote::output_data_t(); }
   virtual cryptonote::tx_out_index get_output_tx_and_index_from_global(const uint64_t& index) const { return cryptonote::tx_out_index(); }
   virtual cryptonote::tx_out_index get_output_tx_and_index(const uint64_t& amount, const uint64_t& index) const { return cryptonote::tx_out_index(); }
   virtual void get_output_tx_and_index(const uint64_t& amount, const std::vector<uint64_t> &offsets, std::vector<cryptonote::tx_out_index> &indices) const {}