BoringSSL

[turuslan]

• add BoringSSL (required for lsquic)
• remove OpenSSL (replaced by BoringSSL)
• add libsecp256k1 (secp256k1 not supported by BoringSSL)

[igor-egorov]

This is perfectly fine and no need to change. Personally, I prefer splitting the line to assign a value of function to a temp variable for making easier possible debugging:

Suggested change

	return secp256k1_ecdsa_verify(ctx_.get(), &ffi_sig, digest.data(), &ffi_pub)
	auto verify_res = secp256k1_ecdsa_verify(ctx_.get(), &ffi_sig, digest.data(), &ffi_pub);
	return verify_res == 1;