RFR: 8303866: Allow ZipInputStream.readEnd to parse small Zip64 ZIP files [v2]

[Eirik Bjorsnos]

> ZipInputStream.readEnd currently assumes a Zip64 data descriptor if the number of compressed or uncompressed bytes read from the inflater is larger than the Zip64 magic value.
> 
> While the ZIP format  mandates that the data descriptor `SHOULD be stored in ZIP64 format (as 8 byte values) when a file's size exceeds 0xFFFFFFFF`, it also states that `ZIP64 format MAY be used regardless of the size of a file`. For such small entries, the above assumption does not hold.
> 
> This PR augments ZipInputStream.readEnd to also assume 8-byte sizes if the ZipEntry includes a Zip64 extra information field. This brings ZipInputStream into alignment with the APPNOTE format spec:
> 
> 
> When extracting, if the zip64 extended information extra 
> field is present for the file the compressed and 
> uncompressed sizes will be 8 byte values.
> 
> 
> While small Zip64 files with 8-byte data descriptors are not commonly found in the wild, it is possible to create one using the Info-ZIP command line `-fd` flag:
> 
> `echo hello | zip -fd > hello.zip`
> 
> The PR also adds a test verifying that such a small Zip64 file can be parsed by ZipInputStream.

Eirik Bjorsnos has updated the pull request incrementally with one additional commit since the last revision:

  Use block comments instead of javadoc comments to avoid doclint warnings

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12524/files
  - new: https://git.openjdk.org/jdk/pull/12524/files/0633c807..01216ef7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12524&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12524&range=00-01

  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/12524.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12524/head:pull/12524

PR: https://git.openjdk.org/jdk/pull/12524