Avoid hash copy.

Author: evoskuil

src/chain/chain_state.cpp

@@ -81,10 +81,12 @@ constexpr bool is_retarget_height(size_t height,
 // These two blocks each have a coinbase transaction that exactly duplicates
 // another that is not spent by the arrival of the corresponding duplicate.
 // Exceptions: block 91842 (duplicates 91812), 91880 (duplicates 91722).
-inline bool is_bip30_exception(const checkpoint& check) NOEXCEPT
+inline bool is_bip30_exception(const hash_digest& hash, size_t height) NOEXCEPT
 {
-    return (check == mainnet_bip30_exception_checkpoint1) ||
-         (check == mainnet_bip30_exception_checkpoint2);
+    return (hash   == mainnet_bip30_exception_checkpoint1.hash() &&
+            height == mainnet_bip30_exception_checkpoint1.height()) ||
+           (hash   == mainnet_bip30_exception_checkpoint2.hash() &&
+            height == mainnet_bip30_exception_checkpoint2.height());
 }
 
 inline uint32_t timestamp_high(const chain_state::data& values) NOEXCEPT
@@ -263,7 +265,7 @@ chain_state::activations chain_state::activation(const data& values,
     // bip30 is disabled by bip30_deactivate and reenabled by bip30_reactivate.
     // Otherwise if not exception, existing duplicate coinbase must be spent.
     if (forks.bip30 && (!bip30_deactivate || bip30_reactivate) &&
-        !is_bip30_exception({ values.hash, height }))
+        !is_bip30_exception(values.hash, height))
     {
         result.flags |= flags::bip30_rule;
     }