RFR: 8370254: Add VM_MEMORY_JAVA mmap tag to MacOS mmap calls [v6]

[Nityanand Rai]

> Add VM_MEMORY_JAVA tag to mmap calls in os_bsd.cpp for better memory tracking of java process on macOs

Nityanand Rai has updated the pull request incrementally with one additional commit since the last revision:

  minor refactoring to reduce code duplication

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27868/files
  - new: https://git.openjdk.org/jdk/pull/27868/files/2322badf..183927b0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27868&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27868&range=04-05

  Stats: 42 lines in 3 files changed: 12 ins; 24 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/27868.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27868/head:pull/27868

PR: https://git.openjdk.org/jdk/pull/27868