[clang] [llvm] [LinkerWrapper] Always pass `-flto` if the linker supports it (PR #102972)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Cases that used to compile successfully (even if more optimized than expected) will no longer. Sounds like a regression.

It kind of is, but I don't think we should work around backend bugs in the clang driver.

https://github.com/llvm/llvm-project/pull/102972