RFR: 8281507: Two javac tests have bad jtreg `@clean` tags

[Aleksey Shipilev]

Apparently, jtreg does not support `*` globbing. It now throws errors for upcoming jtreg 7.

Additional testing:
 - [x] Affected tests still pass

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

Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/7398/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7398&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281507
  Stats: 6 lines in 2 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7398.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7398/head:pull/7398

PR: https://git.openjdk.java.net/jdk/pull/7398