[lld] [llvm] [lld][MachO] Follow-up to use madvise() for threaded file page-in. (PR #157917)

[Richard Smith via llvm-commits]

zygoloid wrote:

> Object files are a multiple of the page size no?

If so, any code opening them as a memory buffer really shouldn't be passing `RequiresNullTerminator = true`, or it [will never use mmap](https://github.com/zygoloid/llvm-project/blob/62187a60e61017c3a453bb138d27f9bdda27879d/llvm/lib/Support/MemoryBuffer.cpp#L401), regardless of #152595. `RequiresNullTerminator = true` is the wrong default.

https://github.com/llvm/llvm-project/pull/157917