[flang-commits] [flang] [flang] Move `genCommonBlockMember` from OpenMP to ConvertVariable, NFC (PR #74488)

[Krzysztof Parzyszek via flang-commits]

kparzysz wrote:

The build failures are caused by lit on Windows not being able to open four of the test files, e.g.
```
OSError: [Errno 22] Invalid argument: 'C:\\ws\\src\\flang\\test\\Lower\\OpenMP\\FIR\\declare-target-implicit-func-and-subr-cap-enter.f90'
```

https://github.com/llvm/llvm-project/pull/74488