RFR: JDK-8261609: remove remnants of XML-driven builders

[Jonathan Gibbons]

Small change to remove some long-dead code, related to a long-dead feature to configure the generated output by means of XML files.

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Commit messages:
 - JDK-8261609: remove remnants of XML-driven builders

Changes: https://git.openjdk.java.net/jdk/pull/2534/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2534&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261609
  Stats: 22 lines in 1 file changed: 0 ins; 22 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2534.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2534/head:pull/2534

PR: https://git.openjdk.java.net/jdk/pull/2534