RFR: 8255526: Enable jcheck whitespace checking of build system files [v2]

[Magnus Ihse Bursie]

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

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Add ignore-tabs

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/898/files
  - new: https://git.openjdk.java.net/jdk/pull/898/files/236d8360..5aa2766b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=898&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=898&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 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