fuzz-journal-remote: print some kinds of errors

fuzz-journal-remote: print some kinds of errors

In https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=34803, we fail with:

  Assertion 'IN_SET(r, -ENOMEM, -EMFILE, -ENFILE)' failed at src/journal-remote/fuzz-journal-remote.c:69,
    function int LLVMFuzzerTestOneInput(const uint8_t *, size_t)(). Aborting.
  AddressSanitizer:DEADLYSIGNAL

Let's try to print the error, so maybe we can see what is going on.
With the previous commit we shouldn't print out anything.