RFR: jcheck: remove unused code

[Erik Helin]

Hi all,

please review this patch that removes some very old code in `JCheck` that has never been used and just clutters the
`JCheck` API. We have other ways of ensuring whether a certain commit should or should not be allowed to be pushed, the
code that this patch removes is not used.

This is a fully backwards compatible change with both older and newer .jcheck/conf files.

Testing:
- [x] `make test` passes on Linux x64
- [x] `make images` passes on Linux x64

Thanks,
Erik

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Commit messages:
 - jcheck: remove unused blacklist and whitelist code

Changes: https://git.openjdk.java.net/skara/pull/805/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=805&range=00
  Stats: 269 lines in 11 files changed: 0 ins; 260 del; 9 mod
  Patch: https://git.openjdk.java.net/skara/pull/805.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/805/head:pull/805

PR: https://git.openjdk.java.net/skara/pull/805