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

[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.

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Commit messages:
 - 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

Changes: https://git.openjdk.java.net/jdk/pull/2222/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2222&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260282
  Stats: 92 lines in 3 files changed: 89 ins; 0 del; 3 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