Rollup merge of #52019 - michaelwoerister:cross-lto-auto-plugin, r=alexcrichton

Rollup merge of #52019 - michaelwoerister:cross-lto-auto-plugin, r=alexcrichton

[cross-lang-lto] Allow the linker to choose the LTO-plugin (which is useful when using LLD)

This PR allows for not specifying an LTO-linker plugin but still let `rustc` invoke the linker with the correct plugin arguments. This is useful when using LLD which does not need the `-plugin` argument. Since LLD is the best linker for this scenario anyway, this change should improve ergonomics quite a bit.

r? @alexcrichton