How add new options without sacrificing backward compatibility

[dgeorge83616]

PR #3983 dramatically improves cppcheck usability by limiting checks to the buffer file by adding --file-filter option whenever handlers/cppcheck.vim adds the --project option. Unfortunately, older versions of cppcheck will not recognize the new option and exit. Can someone suggest and ale-approved way of handling the backward compatibility?

See also: Check files matching a given filter

[dgeorge83616]

AMOQ: The --file-filter cppcheck option is not new and present tests pass when using it. Not a issue, after all.