RFR: 8244706: GZIP "OS" header flag hard-coded to 0 instead of 255 (RFC 1952 non-compliance) [v3]

[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

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  Improve the comment for the OS_UNKNOWN field

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/130/files
  - new: https://git.openjdk.java.net/jdk/pull/130/files/159684de..7679b119

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=130&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=130&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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