RFR: Fixed validate target

[Jesper Wilhelmsson]

Validate target is broken after build remake.

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Commit messages:
 - Fixed validate target

Changes: https://git.openjdk.java.net/guide/pull/58/files
 Webrev: https://webrevs.openjdk.java.net/?repo=guide&pr=58&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/guide/pull/58.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/58/head:pull/58

PR: https://git.openjdk.java.net/guide/pull/58