RFR: JDK-8303184: ZGC incompatible with ASan

[Justin King]

Update ZGC to work with ASan and fix missing LSan root region registration for ZGC.

Currently all ZGC tests will fail on x86 with ASan enabled, as it is unable to reserve the address regions necessary due to overlap with ASan. x86 does not appear to have the address layout detection logic of the other architectures. Other alternatives are port the address layout detection logic to x86 (I was not comfortable doing this) or just disable ZGC when building Hotspot with ASan.

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Commit messages:
 - Merge remote-tracking branch 'upstream/master' into asan-zgc
 - Register MmapArrayAllocator allocations with LSan
 - Force ZGC to layout 3 with ASan

Changes: https://git.openjdk.org/jdk/pull/13000/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13000&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303184
  Stats: 18 lines in 2 files changed: 16 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13000.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/13000/head:pull/13000

PR: https://git.openjdk.org/jdk/pull/13000