RFR: 8292054: Test runtime/posixSig/TestPosixSig.java fails with 'Test failed bad output.'

[Harold Seigel]

Please review this fix for JDK-8292054.  The existing regression test for JDK-8285792, test/hotspot/jtreg/runtime/posixSig/TestPosixSig.java, intermittently fails because it depends on periodic calls to JVM function os::run_periodic_checks().  This fix replaces test TestPosixSig.java with a gtest that does its own explicit call to os::run_periodic_checks().

The fix was tested by running the new test 150+ times on Linux, Mac OS, and Windows.

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Commit messages:
 - 8292054: Test runtime/posixSig/TestPosixSig.java fails with 'Test failed, bad output.'

Changes: https://git.openjdk.org/jdk/pull/9882/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9882&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292054
  Stats: 228 lines in 3 files changed: 98 ins; 130 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9882.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9882/head:pull/9882

PR: https://git.openjdk.org/jdk/pull/9882