[llvm] [MCParser] .incbin: Don't retain the buffer, don't require NUL termination (PR #196696)

[Alexis Engelke via llvm-commits]

aengelke wrote:

> Also what difference does the Null terminator make?

It prevents the use of mmap in some cases. See shouldUseMmap.

> I added commits for sliced access because the review mentioned that it should be a future task after the bug is fixed.

I said that we should first implement a solution without slicing. Then, we could implement slicing as a separate PR (always under the condition that there's a tangible benefit -- this is implicit for ~everything we do here, especially if we add a fair amount of new code).

https://github.com/llvm/llvm-project/pull/196696