[clang] [PS5][Driver] forward -ffat-lto-objects to the linker (PR #172854)

[Edd Dawson via cfe-commits]

https://github.com/playstation-edd approved this pull request.

LGTM, with a note for posterity:

Ideally we'd be calling `addLTOOptions()`, similar to other drivers. Support for fat LTO would then have been automatic. But that's also true of other LTO-related options and I don't think this update makes our future reconciliation/alignment any more difficult, really.

https://github.com/llvm/llvm-project/pull/172854