refactor(build): use dynamic cpu cores to compile code.

[WoodsCumming]

What is the purpose of the change

Modify the default number of threads used for compilation on Linux and MAC platforms to be the number of CPU logical cores, rather than hardcode.

Brief changelog

Modify the default number of threads used for compilation on Linux and MAC platforms to be the number of CPU logical cores, rather than hardcode.

Verifying this change

Verified. Want a code review.

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