RFR: 8276654: element-list order is non deterministic

[Andrew Leonard]

Fixes: https://bugs.openjdk.java.net/browse/JDK-8276654

A intermittent problem with the make dependencies means the jdk.javadoc element-list-.txt generation can remove the src defined element|package-list-<7,8,9,10>.txt files.
Recreatable by using --with-jobs=1 causing jdk.javadoc "gendata" to always occur after "java" module build dependency.
This fix puts a dependency of jdk.javadoc-java on jdk.javadoc-gendata to avoid this.

Signed-off-by: Andrew Leonard <anleonar at redhat.com>

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Commit messages:
 - 8276654: element-list order is non deterministic

Changes: https://git.openjdk.java.net/jdk/pull/6278/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6278&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276654
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6278.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6278/head:pull/6278

PR: https://git.openjdk.java.net/jdk/pull/6278