[11u] RFR 8217362: Emergency dump does not work when disk=false is set

[董登辉(卓昂)]

Hi all,
  11u has the same problem. Please review this backport, original patch doesn't apply cleanly caused by Hunk FAILED
in test/jdk/jdk/jfr/jvm/TestDumpOnCrash.java and src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp

11u-webrev:
http://cr.openjdk.java.net/~wzhuo/8217362/webrev.00/

Original bug:
https://bugs.openjdk.java.net/browse/JDK-8217362
http://hg.openjdk.java.net/jdk/jdk/rev/3cabb47758c9

Testing: test/jdk/jdk/jfr/jvm/TestDumpOnCrash.java
 
Thanks,
Denghui Dong