RFR: JDK-8270108: Update JCov version to 3.0.9

[Alexandre Iline]

JDK-8270108: Update JCov version to 3.0.9

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Commit messages:
 - JDK-8270108: Update JCov version to 3.0.9

Changes: https://git.openjdk.java.net/jdk/pull/4729/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4729&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270108
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4729.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4729/head:pull/4729

PR: https://git.openjdk.java.net/jdk/pull/4729