Fix compatibility with Boost 1.78

[pwojcikdev]

This PR fixes build errors when building node with Boost version 1.78 and later with AppleClang 13.1.6. Boost 1.78 already provides conversions between boost::system::error_code and std::error_code.

[pwojcikdev]

Compilation errors with current code:

In file included from /Users/piotr/Work/nano-node-dev/nano/lib/diagnosticsconfig.cpp:1:
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/diagnosticsconfig.hpp:3:
/Users/piotr/Work/nano-node-dev/nano/lib/errors.hpp:211:8: error: explicit specialization of 'std::is_error_code_enumboost::system::errc::errc_t' after instantiation
struct is_error_code_enumboost::system::errc::errc_t
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/homebrew/include/boost/system/detail/error_code.hpp:113:21: note: implicit instantiation first required here
|| std::is_error_code_enum::value
^
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/diagnosticsconfig.cpp:2:
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/tomlconfig.hpp:3:
/Users/piotr/Work/nano-node-dev/nano/lib/configbase.hpp:84:11: error: use of overloaded operator '=' is ambiguous (with operand types 'nano::error' and 'nano::error_config')
*error = error_a;
~~~~~~ ^ ~~~~~~~
/Users/piotr/Work/nano-node-dev/nano/lib/tomlconfig.hpp:186:6: note: in instantiation of function template specialization 'nano::configbase::conditionally_set_error<unsigned long, nano::error_config>' requested here
conditionally_set_error (nano::error_config::invalid_value, optional, key);
^
/Users/piotr/Work/nano-node-dev/nano/lib/tomlconfig.hpp:120:3: note: in instantiation of function template specialization 'nano::tomlconfig::get_config<unsigned long, void>' requested here
get_config (true, key, target, target);
^
/Users/piotr/Work/nano-node-dev/nano/lib/diagnosticsconfig.cpp:22:19: note: in instantiation of function template specialization 'nano::tomlconfig::get_optional' requested here
txn_tracking_l->get_optional ("min_read_txn_time", min_read_txn_time_l);
^
/Users/piotr/Work/nano-node-dev/nano/lib/errors.hpp:252:10: note: candidate function
error & operator= (std::error_code code_a);
^
/Users/piotr/Work/nano-node-dev/nano/lib/errors.hpp:253:10: note: candidate function
error & operator= (boost::system::error_code const & code_a);
^

In file included from /Users/piotr/Work/nano-node-dev/nano/lib/epoch.cpp:1:
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/epoch.hpp:3:
/Users/piotr/Work/nano-node-dev/nano/lib/numbers.hpp:360:8: error: no template named 'hash'; did you mean 'std::hash'?
struct hash<std::reference_wrapper<::nano::block_hash const>>
^~~~
std::hash
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk/usr/include/c++/v1/__memory/shared_ptr.h:1710:50: note: 'std::hash' declared here
template struct _LIBCPP_TEMPLATE_VIS hash;
^
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/epoch.cpp:1:
In file included from /Users/piotr/Work/nano-node-dev/nano/lib/epoch.hpp:3:
/Users/piotr/Work/nano-node-dev/nano/lib/numbers.hpp:360:8: error: class template specialization of 'hash' not in a namespace enclosing '__1'
struct hash<std::reference_wrapper<::nano::block_hash const>>
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk/usr/include/c++/v1/__memory/shared_ptr.h:1710:50: note: explicitly specialized declaration is here
template struct _LIBCPP_TEMPLATE_VIS hash;
^

[clemahieu]

Confirmed the existing error but I get a build error with this branch:

/Users/clemahieu/nano-node.src/nano/core_test/toml.cpp:345:30: error: use of overloaded operator '==' is ambiguous (with operand types 'nano::error' and 'nano::error_config')
ASSERT_TRUE (t.get_error () == nano::error_config::missing_value);

[pwojcikdev]

Those build errors are fixed now.