RFR: 1372: Only add security label to jarsigner related files

[Weijun Wang]

Currently, the core-libs and compiler labels are also set. They should be removed.

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Commit messages:
 - 1372: Only add security label to jarsigner related files

Changes: https://git.openjdk.java.net/skara/pull/1294/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1294&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1372
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/skara/pull/1294.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1294/head:pull/1294

PR: https://git.openjdk.java.net/skara/pull/1294