[lld] [LLD][ELF] Skip non-SHF_ALLOC sections when checking max VA and max VA difference in relaxOnce() (PR #145863)

[Fangrui Song via llvm-commits]

MaskRay wrote:

You are right that the SHF_ALLOC condition just skips some check and does not change the behavior. Then why does it matter? Do you find a scenario where having the condition improves performance?

https://github.com/llvm/llvm-project/pull/145863