RFR: 8264827: Large mapped buffer/segment crash the VM when calling isLoaded [v2]

[Chris Hegarty]

> Avoid overflow when calculating the number of pages for large mapped segment sizes.

Chris Hegarty has updated the pull request incrementally with one additional commit since the last revision:

  Skip testing on 32-bit systems

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3378/files
  - new: https://git.openjdk.java.net/jdk/pull/3378/files/1816b200..1dbe4a63

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3378&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3378&range=00-01

  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3378.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3378/head:pull/3378

PR: https://git.openjdk.java.net/jdk/pull/3378