[lld] Allow Arm PC-relative relocations in pic or shared library (PR #77304)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Apologies for the force push, it would have been better to do a fixup but the original version is still visible here on the main page.

Some people don't prefer force pushes but it's not a problem for me :) For shorter patches perhaps it matter even less.

The lld/ELF patches usually have a `[ELF]` tag. Some use a more verbose `[lld][ELF]`.

https://github.com/llvm/llvm-project/pull/77304