RFR: CODETOOLS-7903548: Allow plugins to be compiled into the jcov.jar

[Alexandre Iline]

Allow plugins to be compiled into the jcov.jar

-------------

Commit messages:
 - CODETOOLS-7903548: Allow plugins to be compiled into the jcov.jar

Changes: https://git.openjdk.org/jcov/pull/42/files
 Webrev: https://webrevs.openjdk.org/?repo=jcov&pr=42&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903548
  Stats: 78 lines in 4 files changed: 63 ins; 2 del; 13 mod
  Patch: https://git.openjdk.org/jcov/pull/42.diff
  Fetch: git fetch https://git.openjdk.org/jcov.git pull/42/head:pull/42

PR: https://git.openjdk.org/jcov/pull/42