RFR: 8258576: Try to get zerobased CCS if heap is above 32 and CDS is disabled

[Richard Reingruber]

Please review this small enhancement if CDS is disabled.

It tries to get a zerobased compressed class space if we have a not-zerobased compressed oops heap, i.e. the heap is above 32g. In this case there is a good chance to locate CCS below 32g.

The fix passed our CI testing: JCK and JTREG, also in Xcomp mode, SPECjvm2008, SPECjbb2015, Renaissance Suite,
SAP specific tests with fastdebug and release builds on all platforms

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Commit messages:
 - Compressed class space should be placed below 32G if heap is above.

Changes: https://git.openjdk.java.net/jdk/pull/1815/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1815&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258576
  Stats: 36 lines in 2 files changed: 25 ins; 0 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1815.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1815/head:pull/1815

PR: https://git.openjdk.java.net/jdk/pull/1815