RFR: 8332125: [nmt] Totals in diff report should print out total malloc and mmap diffs

[Sonia Zaldana Calles]

Hi all, 

This PR addresses [8332125](https://bugs.openjdk.org/browse/JDK-8332125) enabling printing total malloc and mmap diffs when printing an NMT diff report. 

Testing: 
- [x] Added test case passes. 

Thanks, 
Sonia

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Commit messages:
 - 8332125: [nmt] Totals in diff report should print out total malloc and mmap diffs

Changes: https://git.openjdk.org/jdk/pull/19373/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19373&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332125
  Stats: 135 lines in 2 files changed: 135 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19373.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19373/head:pull/19373

PR: https://git.openjdk.org/jdk/pull/19373