RFR: 8251942: PrintStream specification is not clear which flush method is automatically invoked

[Brian Burkhalter]

Please review this minor change to the specification of `java.io.PrintStream`. The longstanding behavior for flushing is to invoke the `flush()` method of the underlying `OutputStream` rather than its override but this was not made explicit in the specification.

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Commit messages:
 - 8251942: PrintStream specification is not clear which flush method is automatically invoked

Changes: https://git.openjdk.java.net/jdk/pull/2926/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2926&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8251942
  Stats: 10 lines in 1 file changed: 1 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2926.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2926/head:pull/2926

PR: https://git.openjdk.java.net/jdk/pull/2926