RFR: 8290861: Remove unused field URLJarFile.BUF_SIZE

[Andrey Turbanov]

Static field 'BUF_SIZE' in the class sun.net.[www.protocol.jar.URLJarFile](http://www.protocol.jar.urljarfile/) is unused and can be removed.

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Commit messages:
 - [PATCH] Remove unused field URLJarFile.BUF_SIZE

Changes: https://git.openjdk.org/jdk/pull/9602/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9602&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290861
  Stats: 7 lines in 1 file changed: 0 ins; 3 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/9602.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9602/head:pull/9602

PR: https://git.openjdk.org/jdk/pull/9602