[lld] [lld][COFF] Fix: Merge `.drectve` sections in ObjFile::readSections (PR #86380)

[Rickey Bowers Jr. via llvm-commits]

bitRAKE wrote:

Weird, I run that test here and I get the correct output.
```
File: lto-directives.dll
Format: COFF-x86-64
Arch: x86_64
AddressSize: 64bit
Export {
  Ordinal: 1
  Name: entry
  RVA: 0x1000
}
```

https://github.com/llvm/llvm-project/pull/86380