TestIndexWriterOnJRECrash suffers from JDK-8047340 - needs workarround [LUCENE-6036]

Similar to issues uncovered in [SOLR-6387](https://issues.apache.org/jira/browse/SOLR-6387), TestIndexWriterOnJRECrash does some forking which can hit JDK-8047340 on the turkish locale...

```
[junit4] Suite: org.apache.lucene.index.TestIndexWriterOnJRECrash
[junit4] 2> NOTE: download the large Jenkins line-docs file by running 'ant get-jenkins-line-docs' in the lucene directory.
[junit4] 2> NOTE: reproduce with: ant test -Dtestcase=TestIndexWriterOnJRECrash -Dtests.method=testNRTThreads -Dtests.seed=B2D360EA192CA242 -Dtests.multiplier=2 -Dtests.nightly=true -Dtests.slow=true -Dtests.linedocsfile=/home/jenkins/lucene-data/enwiki.random.lines.txt -Dtests.locale=tr -Dtests.timezone=Africa/Monrovia -Dtests.asserts=true -Dtests.file.encoding=ISO-8859-1
[junit4] ERROR 0.04s J0 | TestIndexWriterOnJRECrash.testNRTThreads <<<
[junit4] > Throwable #1: java.lang.Error: posix_spawn is not a supported process launch mechanism on this platform.
[junit4] > at __randomizedtesting.SeedInfo.seed([B2D360EA192CA242:290A74F158D7B429]:0)
[junit4] > at java.lang.UNIXProcess$1.run(UNIXProcess.java:111)
[junit4] > at java.lang.UNIXProcess$1.run(UNIXProcess.java:93)
[junit4] > at java.security.AccessController.doPrivileged(Native Method)
[junit4] > at java.lang.UNIXProcess.(UNIXProcess.java:91)
[junit4] > at java.lang.ProcessImpl.start(ProcessImpl.java:130)
[junit4] > at java.lang.ProcessBuilder.start(ProcessBuilder.java:1028)
[junit4] > at org.apache.lucene.index.TestIndexWriterOnJRECrash.forkTest(TestIndexWriterOnJRECrash.java:113)
[junit4] > at org.apache.lucene.index.TestIndexWriterOnJRECrash.testNRTThreads(TestIndexWriterOnJRECrash.java:59)
[junit4] > at java.lang.Thread.run(Thread.java:745)
```

https://bugs.openjdk.java.net/browse/JDK-8047340

---
Migrated from [LUCENE-6036](https://issues.apache.org/jira/browse/LUCENE-6036) by Chris M. Hostetter (@hossman), resolved Oct 30 2014
Attachments: [LUCENE-6036.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-6036/LUCENE-6036.patch)
Linked issues:
- [SOLR-6387](https://issues.apache.org/jira/browse/SOLR-6387)