Add option to allow #[link] directives to be ignored

[jsgf]

In a non-Cargo build system (eg Buck) dependencies on native libraries are already defined in the build system. As such the build system will automatically put those libraries on the link line, which means that rustc should not do so. It would be nice to have an option to allow this (proposal: -Zlink-native-libraries=yes/no, to be stabilized as -Clink-native-libraries=yes/no).

Idea mentioned in #64191
cc @cramertj

[jsgf]

Resolved by #70095