3c14034c55
As per OpenMP 5.2/6.0 the below are valid device values in a `#pragma
omp target` directive:
omp_initial_device (-1) -> refers to the host CPU.
omp_invalid_device (-2) -> an intentionally invalid device, used to
trigger a runtime error.
For the 2 values discussed above flang fails with:
```
error: The device expression of the DEVICE clause must be a positive integer expression
!$OMP TARGET DEVICE(-1)
error: Must have INTEGER type, but is REAL(4)
!$OMP TARGET DEVICE(OMP_INVALID_DEVICE)
```
Issue: https://github.com/llvm/llvm-project/issues/192989