[flang-commits] [flang] [flang][OpenACC] Reland data-clause designator path handling (PR #220781)

[Eugene Epshteyn via flang-commits]

eugeneepshteyn wrote:

Dropped diagnostics?

```fortran
subroutine cb()
  integer :: a, b
  common /cbx/ a, b
  !$acc parallel copy(/cbx/) private(/cbx/)
  a = 1
  !$acc end parallel
end subroutine
```

This PR silently accepts it. Before this PR, there was this diagnostics:
```
s4-common-block.f90:4:39: error: 'cbx' appears in more than one data-sharing clause on the same OpenACC directive
```

https://github.com/llvm/llvm-project/pull/220781