[jdk17u-dev] RFR: 7036144: GZIPInputStream readTrailer uses faulty available() test for end-of-stream

[Todd V. Jonker]

This is a clean backport of [d3f3011](https://github.com/openjdk/jdk/commit/d3f3011d56267360d65841da3550eca79cf1575b), originally authored by @archiecobbs and reviewed by @jaikiran

The corresponding backport for JDK21 is https://github.com/openjdk/jdk21u-dev/pull/1897

Testing:
- [x] New regression test fails without the fix, passes with it
- [x] linux-x86_64-server-release: headless tiers 1-3

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Commit messages:
 - Backport d3f3011d56267360d65841da3550eca79cf1575b

Changes: https://git.openjdk.org/jdk17u-dev/pull/3667/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3667&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-7036144
  Stats: 111 lines in 2 files changed: 96 ins; 9 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3667.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3667/head:pull/3667

PR: https://git.openjdk.org/jdk17u-dev/pull/3667