[lld] [lld][MachO]Multi-threaded i/o. Twice as fast linking a large project. (PR #147134)

[Ellis Hoag via llvm-commits]

ellishg wrote:

By the way, I found `TaskQueue` in `Support/` which seems to do what we want. Could we use that?
 https://github.com/microsoft/llvm/blob/f270d88e8d2c496285111e9a600513d460df4633/include/llvm/Support/TaskQueue.h#L32-L35

https://github.com/llvm/llvm-project/pull/147134