[lld] [llvm] Rename `F_no_mmap` to `F_mmap` (PR #134787)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> So I suppose we should set `OF_Delete` accordingly, does that sound correct? If you agree with my findings, I'd be happy to create a PR and small associated test.

Thanks for the investigation! I think I'm lost in the Windows details (I am not familiar with it) but please create a PR and update the test :)

https://github.com/llvm/llvm-project/pull/134787