Linkage error on macos

[SchrodingerZhu]

I am still not able to run tests of this library on macos:

1. the default c++ standard library on macos should be c++ instead of stdc++.
2. the linker on macos does not understand --{start/end}-group.
3. the linker on macos is not happy about the duplicate main symbol inside libLake.a.

[digama0]

(3) sounds like a general issue with Lake that should be brought up upstream.