No need to pass C++ library

[arnetheduck]

C++ compilers will choose this themselves - which one is used depends on how the C++ compiler is configured, not the platform - if the wrong one is passed in, as happens for clang+windows (which uses -lc++), the application using lsquic fails to link due to duplicate symbols

[arnetheduck]

Notably, -l is a linker flag, typically passed in with {.passl.} - but more importantly, as long as the C++ compiler is used to link the final output, the c++ std lib will automatically be chosen correctly.

The trick is to use C++ to link - nim does this automatically when running nim c ... but if makefiles etc are used for the final linking, one needs to be a bit more careful and not accidentally use a c compiler driver for the linking.