[jdk16u] RFR: 8226810: Failed to launch JVM because of NullPointerException occured on System.props

[Evan Whelan]

This simple backport enables the GB18030 charset to be built into java.base on Windows.

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Commit messages:
 - 8226810: Failed to launch JVM because of NullPointerException occured in System.props

Changes: https://git.openjdk.java.net/jdk16u/pull/4/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16u&pr=4&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8226810
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk16u/pull/4.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16u pull/4/head:pull/4

PR: https://git.openjdk.java.net/jdk16u/pull/4