RFR: 8304836: Make MALLOC_MIN4 macro more robust [v2]

[Naoto Sato]

> The current macro assumes the argument is `jint` because all locations pass `jint`. However, this would not work if a wider type such as `jlong` is passed. Removing the `unsigned` cast and make the condition explicit would make the macro more robust.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Update src/java.base/share/native/libjava/jni_util.c
  
  Co-authored-by: David Schlosnagle <schlosna at gmail.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13564/files
  - new: https://git.openjdk.org/jdk/pull/13564/files/1a4ff652..0c97bf66

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13564&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13564&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13564.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13564/head:pull/13564

PR: https://git.openjdk.org/jdk/pull/13564