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

[David Spickett via llvm-commits]

DavidSpickett wrote:

Our no threading build appears to be fixed but I got an ASAN failure with that change in a threading build: https://lab.llvm.org/buildbot/#/builders/24/builds/13751

Which "fixed" itself in the next build. So I think this is related to:
> The new PR moves to use madvise() instead of the ad-hoc page referencing code I wrote which should avoid SIGSEGVs if the buffer is deallocated.

And therefore I have left my fixes in and disabled the test everywhere for now.

It could be my fault, but I presume you'll start by reverting all my changes anyway in favour of this PR so same result either way.

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