RFR: 8255526: Enable jcheck whitespace checking of build system files

[Magnus Ihse Bursie]

With the new Skara tooling, we can finally enable whitespace testing for build system files (makefiles and autoconf files).

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Commit messages:
 - 8255526: Enable jcheck whitespace checking of build system files

Changes: https://git.openjdk.java.net/jdk/pull/898/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=898&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255526
  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/898.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/898/head:pull/898

PR: https://git.openjdk.java.net/jdk/pull/898