bug#55354: 29.0.50; check-declare-directory shouldn't error if there are no c-f statements

[Jonas Bernoulli]

check-declare-directory shouldn't raise an error if there are no
declare-function statements.

That would allow always running c-d-d from, e.g., a Makefile, without
having to remove support for running check-declare-directory when
removing the last declare-function statement and then having to add
it again when later adding a new statement.

This could be done by using process-lines-ignore-status instead of
process-lines in check-declare-directory.

     Cheers,
     Jonas