[lld] Make hashtable entry size configurable (PR #113431)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I still share concern with the extra complexity to the generic legacy DT_HASH.
As an alternative, could we explore a simpler workaround where `--hash-style=both` is interpreted as 'gnu' for s390x?

FYI, I've already added DT_GNU_HASH support to the Linux kernel selftests: https://github.com/torvalds/linux/commit/e0746bde6f820a6239628a5c17653b5c3c3d56df


https://github.com/llvm/llvm-project/pull/113431