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

[Daniel Rodríguez Troitiño via llvm-commits]

drodriguez wrote:

> 've included changes to two additional files to counter the performance regression of 2 seconds from 85cd3d98686c47d015dbcc17f1f7d0714b00e172 for the linker when using the --worker-threads option due to not mmap()ing many input files. Binary object and archive files don't need to be null terminated. This seemed the least intrusive change.

The one in `InputFiles.cpp` is also used for tbd files, if I am not mistaken. Those are textual files (YAML and recently JSON), and I am not sure if the parser might be tripped from the missing `\0` towards the end if the situation described in 85cd3d98686c47d015dbcc17f1f7d0714b00e172 happens.

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