RFR: JDK-8260282: Add option to compress heap dumps created by -XX:+HeapDumpOnOutOfMemoryError [v2]

[Ralf Schmelter]

> This change adds the optiont to created a gzipped heap dump by -XX:+HeapDumpOnOutOfMemoryError.
> 
> -XX:HeapDumpGzipLevel=<level> sets the compression level. 0 (the default) means no gzipping of the dump. Otherwise the level has to be between 1 and 10.

Ralf Schmelter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - Merge branch 'master' of https://github.com/openjdk/jdk into JDK-8260282
 - Fixed maximum supported compression level.
 - Fixed trailing whitespace.
 - Merge branch 'master' of https://github.com/openjdk/jdk into JDK-8260282
 - Change allowed levels. 0 now means disabled.#
 - Added option to compress the heap dump created by -XX:+HeapDumpOnOutOfMemoryError

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2222/files
  - new: https://git.openjdk.java.net/jdk/pull/2222/files/88b00e00..3bf02689

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2222&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2222&range=00-01

  Stats: 328 lines in 12 files changed: 294 ins; 11 del; 23 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2222.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2222/head:pull/2222

PR: https://git.openjdk.java.net/jdk/pull/2222