RFR: 8292054: Test runtime/posixSig/TestPosixSig.java fails with 'Test failed, bad output.' [v2]

[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.

Harold Seigel has updated the pull request incrementally with one additional commit since the last revision:

  Improve gtest based on review comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9882/files
  - new: https://git.openjdk.org/jdk/pull/9882/files/b56bd913..4e9afcd3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9882&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9882&range=00-01

  Stats: 44 lines in 6 files changed: 3 ins; 21 del; 20 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