[lld] [PAC][lld][AArch64][ELF] Support signed TLSDESC (PR #113817)

[Fangrui Song via llvm-commits]

================
@@ -1337,7 +1363,9 @@ unsigned RelocationScanner::handleTlsRelocation(RelExpr expr, RelType type,
     // set NEEDS_TLSDESC on the label.
     if (expr != R_TLSDESC_CALL) {
       if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
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MaskRay wrote:

```
if (aarch64) ...;
else if (!isRISCV || type == ...) ...;
```

https://github.com/llvm/llvm-project/pull/113817