net/mpich: unbreak optimized runtime after 88e134883dd2

Runtime may fail without a L0 driver like intel-compute-runtime e.g.,

$ mpivars
Abort(268484367) on node 0 (rank 0 in comm 0): Fatal error in PMPI_Init_thread: Other MPI error, error stack:
MPIR_Init_thread(153): gpu_init failed
[unset]: write_line error; fd=-1 buf=:cmd=abort exitcode=268484367
:
system msg for write_line failure : Bad file descriptor
Attempting to use an MPI routine before initializing MPICH

$ MPIR_CVAR_ENABLE_GPU=0 mpivars
Abort(2139535) on node 0 (rank 0 in comm 0): Fatal error in PMPI_Init_thread: Other MPI error, error stack:
MPIR_Init_thread(159)......:
MPID_Init(591).............:
MPIDI_SHM_mpi_init_hook(22):
MPIDI_IPC_mpi_init_hook(36):
MPIDI_GPU_mpi_init_hook(79): gpu_get_dev_count failed
[unset]: write_line error; fd=-1 buf=:cmd=abort exitcode=2139535
:
system msg for write_line failure : Bad file descriptor
Abort(2139535) on node 0 (rank 0 in comm 0): Fatal error in PMPI_Init_thread: Other MPI error, error stack:
MPIR_Init_thread(159)......:
MPID_Init(591).............:
MPIDI_SHM_mpi_init_hook(22):
MPIDI_IPC_mpi_init_hook(36):
MPIDI_GPU_mpi_init_hook(79): gpu_get_dev_count failed
[unset]: write_line error; fd=-1 buf=:cmd=abort exitcode=2139535
:
system msg for write_line failure : Bad file descriptor
Segmentation fault

PR: 256244 (for tracking)