[lld] [lld] enable installing lld headers as part of distribution (PR #127123)

[Maksim Levental via llvm-commits]

makslevental wrote:

> LLVM_DISTRIBUTION_COMPONENTS=clang;clang-headers;lld installs clang headers. This PR makes lld-headers installs lld headers.

Sorry I don't understand `This PR makes lld-headers installs lld headers.`. Do you mean that `LLVM_DISTRIBUTION_COMPONENTS=clang;clang-headers;lld` shouldn't install `lld-headers`?

https://github.com/llvm/llvm-project/pull/127123