RFR: 8244706: GZIP "OS" header flag hard-coded to 0 instead of 255 (RFC 1952 non-compliance)

[Jaikiran Pai]

Can I please get a review and a sponsor for this patch which fixes the issue reported in
https://bugs.openjdk.java.net/browse/JDK-8244706?

The commit here sets the `OS` header flag to `255` (which represents `unknown`) as noted in [1]. A new test has been
included in this commit to verify the change. Furthermore, this doesn't impact the `java.util.zip.GZIPInputStream`
since it ignores [2] this header value while reading the headers from the stream.

[1] https://tools.ietf.org/html/rfc1952#page-7
[2] https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/util/zip/GZIPInputStream.java#L173

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Commit messages:
 - 8244706: GZIP "OS" header flag hard-coded to 0 instead of 255 (RFC 1952 non-compliance)

Changes: https://git.openjdk.java.net/jdk/pull/130/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=130&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244706
  Stats: 82 lines in 2 files changed: 79 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/130.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/130/head:pull/130

PR: https://git.openjdk.java.net/jdk/pull/130