RFR: 8251400: Fix incorrect addition of library to test in JDK-8237858

[Magnus Ihse Bursie]

In JDK-8237858, -pthread was added to all native tests, instead of the one single test that needed it. In the meantime, two new tests with pthread dependencies has crept in unnoticed due to this.

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Commit messages:
 - 8251400: Fix incorrect addition of library to test in JDK-8237858

Changes: https://git.openjdk.java.net/jdk/pull/6682/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6682&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8251400
  Stats: 13 lines in 2 files changed: 5 ins; 7 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6682.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6682/head:pull/6682

PR: https://git.openjdk.java.net/jdk/pull/6682