RFR: JDK-8317959: Check return values of malloc in native java.base coding

[Matthias Baesken]

There are a few remaining places in java.base where the return value NULL-check of malloc is missing. This should better be adjusted.

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Commit messages:
 - JDK-8317959

Changes: https://git.openjdk.org/jdk/pull/16160/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16160&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317959
  Stats: 26 lines in 4 files changed: 24 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16160.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16160/head:pull/16160

PR: https://git.openjdk.org/jdk/pull/16160