[jdk18u] RFR: 8284033: Leak XVisualInfo in getAllConfigs in awt_GraphicsEnv.c

[Zhengyu Gu]

A clean, low risk backport that fixes a memory leak.

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Commit messages:
 - Backport 36b3bbc53de074647ce04de890dc99bd5a2373e8

Changes: https://git.openjdk.java.net/jdk18u/pull/104/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=104&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284033
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/104.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/104/head:pull/104

PR: https://git.openjdk.java.net/jdk18u/pull/104