[foreign-abi] RFR: 8248421: CSupport should have a way to free memory allocated outside Java [v3]

[Athijegannathan Sundararajan]

> Added CSupport.freeMemoryRestricted utility method.

Athijegannathan Sundararajan has updated the pull request incrementally with one additional commit since the last
revision:

  Changed TestNative to use CSupport alloc/free methods instead of native methods.

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/281/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/281/files/e64b7d2e..453b755a

Webrevs:
 - full: https://webrevs.openjdk.java.net/panama-foreign/281/webrev.02
 - incr: https://webrevs.openjdk.java.net/panama-foreign/281/webrev.01-02

  Stats: 24 lines in 2 files changed: 6 ins; 10 del; 8 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/281.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/281/head:pull/281

PR: https://git.openjdk.java.net/panama-foreign/pull/281