add openSSL_ROOT_DIR check on macos

[lqxhub]

What problem does this PR solve?

Issue Number: #2714

Problem Summary:
On macos, originally it was mandatory to set OPENSSL_ROOT_DIR to /usr/local/opt-openssl, but now a judgment is added, only if OPENSSL_ROOT_DIR is not set. Is set to /usr/local/opt-openssl

What is changed and the side effects?

Changed:

Added a judgment to the cmake file

Side effects:

• Performance effects(性能影响): NO

• Breaking backward compatibility(向后兼容性): YES

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Check List:

• Please make sure your changes are compilable(请确保你的更改可以通过编译).
• When providing us with a new feature, it is best to add related tests(如果你向我们增加一个新的功能, 请添加相关测试).
• Please follow Contributor Covenant Code of Conduct.(请遵循贡献者准则).

[chenBright]

LGTM