fix: rid of UB and memory leak based on clang warnings

[knst]

• fixed UB with reading unitialized data from buffer and compare by memcmp
• fix: add missing final and virtual destructor to avoid memory leak.

It also removes several clang's warnings during build.

[PastaPastaPasta]

I think this should be done upstream

[knst]

I think this should be done upstream

• https://github.com/Chia-Network/bls-signatures/pull/358
• https://github.com/Chia-Network/bls-signatures/pull/359

[github-actions[bot]]

'This PR has been flagged as stale due to no activity for over 60 days. It will not be automatically closed, but it has been given a stale-pr label and should be manually reviewed.'

[knst]

@PastaPastaPasta that 2 PR are dead in Chia's repo.

Can you review and merge this PR instead waiting them get merged and backported later?

[UdjinM6]

superseded by #83