RFR: 8340571: Outline code from the loop in ZipFile.Source.initCen [v3]

[Claes Redestad]

> This PR suggests refactoring `ZipFile.Source.initCEN` to move as much logic as possible into the per-entry method processor. This inner method will be called often and JIT optimized earlier in the bootstrap sequence.
> 
> Startup tests using the OpenJDK benchmarks.jar show a ~1ms improvement on both my M1 macbook and my x64 wokstation, while we also improve on relevant throughput microbenchmarks:
> 
> 
> Name               (size) Cnt       Base      Error        Test      Error  Unit  Change
> openCloseZipFile      512  15  61372.449 ± 1197.432   58081.423 ± 1751.988 ns/op   1.06x (p = 0.000*)
> openCloseZipFile     1024  15 117953.727 ± 3202.274  112548.875 ± 5126.665 ns/op   1.05x (p = 0.001*)
> openCloseZipFilex2    512  15  62141.795 ±  674.121   60520.017 ± 2438.346 ns/op   1.03x (p = 0.017 )
> openCloseZipFilex2   1024  15 117959.071 ± 1528.426  111773.937 ± 1604.412 ns/op   1.06x (p = 0.000*)
>   * = significant

Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:

  Typo

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21133/files
  - new: https://git.openjdk.org/jdk/pull/21133/files/f0011e4c..e226b5da

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21133&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21133&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21133.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21133/head:pull/21133

PR: https://git.openjdk.org/jdk/pull/21133