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

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Allow Arm PC-relative relocations in pic or shared library

PIC links include both `-pie` and `-shared`.
`-shared` is for shared libraries.
So "pic or shared library" is redundant not so accurage. 

Perhaps `Allow ... in PIC links.`

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