Ignore asan warnings (clang)

[ctummon]

Wanted to test out my WSL dev environment with Visual Code so took a crack at some of the address sanitizer warnings

1.) Added function attribute to ignore false unsigned int overflow warnings which fixes:
#3658
#3659

2.) Added blacklist file for Clang Address Sanitizer.

Also when running Address Sanitizer with core_test aborts in a couple of places:

config_a.network_params.network.is_dev_network () 
nano::confirmation_solicitor::{ctor}
nano::active_transactions::request_confirm()

config.network_params.network.is_dev_network ()
void nano::node::ongoing_backlog_population ()

It doesn't like that network_params is a reference and it is being accessed on different threads.

Is this a known issue or should I create a new issue?

[ctummon]

I don't think this file was used, correct me if I'm wrong

[ctummon]

-fsanitize-blacklist and -fsanitize=integer only seem to be available with Clang so I added some checks

[ctummon]

OSX (RocksDB) is failing on core_test: error code '124' after "active_transactions.fork_filter_cleanup" looks like a false positive?

Same error for the code of conduct PR:
https://github.com/nanocurrency/nano-node/runs/6762524136?check_suite_focus=true