[jdk18u] RFR: 8282628: Potential memory leak in sun.font.FontConfigManager.getFontConfig()

[Zhengyu Gu]

A clean backport to fix a memory

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Commit messages:
 - Backport 5df2a057707eb65148f96710bd57d8dd8d85d1ed

Changes: https://git.openjdk.java.net/jdk18u/pull/56/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=56&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282628
  Stats: 5 lines in 1 file changed: 2 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/56.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/56/head:pull/56

PR: https://git.openjdk.java.net/jdk18u/pull/56