RFR: 8257234 : Add gz option to SA jmap to write a gzipped heap dump [v16]

[Lin Zang]

> 8257234 : Add gz option to SA jmap to write a gzipped heap dump

Lin Zang has updated the pull request incrementally with two additional commits since the last revision:

 - add test in HeapDumpTest and fix in argument parsing
 - revert changes in jcmd jmap
   
   Another PR has been created for jcmd jmap.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1712/files
  - new: https://git.openjdk.java.net/jdk/pull/1712/files/0aa703d3..8f38b974

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1712&range=15
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1712&range=14-15

  Stats: 114 lines in 6 files changed: 58 ins; 26 del; 30 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1712.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1712/head:pull/1712

PR: https://git.openjdk.java.net/jdk/pull/1712