[Patch, Fortran] PR fortran/38887: Fix MVBITS with runtime zero-length array

[Tobias Burnus]

Daniel Kraft wrote:
> this "trivial" patch fixes PR 38887, where a call to MVBITS aborted at
> runtime if the array was empty (but this not detected at runtime).
>
> I did exclude the regenerated files from the patch, hope this is ok.
> Regression-testing on gnu/linux-x86-32 (but there shouldn't be any) at
> the moment.  Ok for trunk if no failures?
OK. Thanks for the quick patch, which leaves us with only one
non-suspended, non-I/O-performance 4.4 regression (ice-on-valid also
with MVBITS; PR 38883). The general serious regressions status is 95 PRs
of which are 4 P1 and 4 have to be triaged (P3).

Tobias