Drop clang emplace_back workaround.

Author: evoskuil

src/protocols/protocol_block_in.cpp

@@ -248,14 +248,13 @@ get_blocks protocol_block_in::create_get_inventory(
 get_data protocol_block_in::create_get_data(
     const inventory& message) const NOEXCEPT
 {
-    // clang emplace_back bug (no matching constructor), using push_back.
     // bip144: get_data uses witness constant but inventory does not.
 
     get_data getter{};
     getter.items.reserve(message.count(type_id::block));
     for (const messages::inventory_item& item: message.items)
         if ((item.type == type_id::block) && !archive().is_block(item.hash))
-            getter.items.push_back({ block_type_, item.hash });
+            getter.items.emplace_back(block_type_, item.hash);
 
     getter.items.shrink_to_fit();
     return getter;

src/protocols/protocol_block_in_31800.cpp

@@ -257,10 +257,9 @@ get_data protocol_block_in_31800::create_get_data(
     data.items.reserve(map.size());
 
     // bip144: get_data uses witness constant but inventory does not.
-    // clang emplace_back bug (no matching constructor), using push_back.
     std::for_each(map.pos_begin(), map.pos_end(), [&](const auto& item) NOEXCEPT
     {
-        data.items.push_back({ block_type_, item.hash });
+        data.items.emplace_back(block_type_, item.hash);
     });
 
     return data;