llvm 20.1.7, openmpi 5.0.5: llvm/20.1.7/openmpi-5.0.5/lib/mpi_f08.mod":429:24): 'hlfir.declare' op of numeric, logical, or assumed type entity must not have length parameters

Trying to build hdf 1.14.6 with llvm 20.1.7 and openmpi 5.0.5, I get this error:

```
error: loc("/llvm/20.1.7/openmpi-5.0.5/lib/mpi_f08.mod":429:24):
'hlfir.declare' op of numeric, logical, or assumed type entity
must not have length parameters
error: verification of lowering to FIR failed
make[2]: *** [Makefile:1336: mpi_param.o] Error 1
```

I see something related in this llvm forum: https://discourse.llvm.org/t/hlfir-declare-op-of-numeric-logical-or-assumed-type-entity-must-not-have-length-parameters/83629
but I'm not sure it's exactly the same issue.

I can't remember now if I ever built hdf5 with stock llvm successfully or not.

Grateful for any hint or analysis