RFR (S) 8243244: CSR Add option to jcmd to write a gzipped heap dump

[Schmelter, Ralf]

Hi,

I need a review for the following CSR: 
https://bugs.openjdk.java.net/browse/JDK-8243244

It describes the two additional options added to the GC.heap_dump command to 
support gzipped heap dumps.

Best regards,
Ralf