RFR: JDK-8269092: Add OldObjectSampleEvent.allocationSize field [v2]

[Ludovic Henry]

> The data is already available in ObjectSample.allocated and getting this data
> in another way is complicated (via Instrumentation for example). Having the
> size of the objects also allows to augment the memory leak analysis based on
> the object size impact on top of based on the object count impact.

Ludovic Henry has updated the pull request incrementally with two additional commits since the last revision:

 - Add some more cases to TestObjectSize
 - Update according to review

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4549/files
  - new: https://git.openjdk.java.net/jdk/pull/4549/files/ddc9f33f..42914bd1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4549&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4549&range=00-01

  Stats: 216 lines in 4 files changed: 123 ins; 91 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4549.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4549/head:pull/4549

PR: https://git.openjdk.java.net/jdk/pull/4549