[lld] [lld/ELF] Place large executable sections at the end (PR #70358)

[Fangrui Song via llvm-commits]

MaskRay wrote:

The x86-64 ABI mentions `.ltext`, but there is no toolchain support or GNU ld support. I have clarified large data for the x86-64 large code model but not done anything related to `.ltext`. Things like `.lgot` and `.plt` are for theoretic exercise. Their presence in the ABI does not mean a linker needs to implement it. I intentionally do not handle `.ltext` in https://reviews.llvm.org/D150510

I believe `.ltext` is not useful, possibly forever (or 10+ years) and we should hold off adding any lld/ELF code.

This change may also break certain user expectation of the `_end` symbol (end of data).

https://github.com/llvm/llvm-project/pull/70358