IntelLLVM: Make explicit Fortran preprocessing under Ninja more robust

Tell the Fortran compiler to write preprocessor output directly to a
file, as we do for the GNU compiler.  The previous "redirect stdout"
approach could break during ABI detection with some `mpif90` wrappers
that add version information to stdout when called with `-v`.

Issue: #21828
44 jobs for !5826 with intel-fortran-preprocess in 5 minutes and 13 seconds (queued for 2 seconds)
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