RFR: cli: better handling of git-jcheck --lax

[Erik Helin]

Hi all,

please review this PR that handles "lax" for JCheck much better, both when it
comes to CLI reporting and for configuration parsing. Running `git jcheck --lax`
will now hide a number of issues. The "legacy" JCheck parser now also
understands the `comments = lax` configuration property.

Testing:
- `make test` passes on Linux x64
- Manual testing of `git jcheck --lax`

Thanks,
Erik

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Commit messages:
 - cli: better handling of git-jcheck --lax

Changes: https://git.openjdk.java.net/skara/pull/530/files
 Webrev: https://webrevs.openjdk.java.net/skara/530/webrev.00
  Stats: 42 lines in 5 files changed: 24 ins; 0 del; 18 mod
  Patch: https://git.openjdk.java.net/skara/pull/530.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/530/head:pull/530

PR: https://git.openjdk.java.net/skara/pull/530