Add `-headerpad` to linker args

Stream: lean4 dev

[Leni Aniva]

The binary toolchains fail to patch on Nix Darwin: https://github.com/lenianiva/lean4-nix/issues/76, and it could only be fixed by inserting this flag to ld when building the binary toolchain.

This isn't an issue when building from source. Would it be possible to add this to Lean?

[Leni Aniva]

PR here: https://github.com/leanprover/lean4/pull/11623