RFR: 8364768: JDK javax.imageio ImageWriters do not all flush the output stream [v2]

[Phil Race]

> 4 of the 6 JDK ImageWriters flush the stream at the end of writing. 2 (TIFF and GIF) do not. 
> 
> This will matter if you are using a caching ImageOutputStream.
> 
> This fix makes it consistent.

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  8364768

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26703/files
  - new: https://git.openjdk.org/jdk/pull/26703/files/ffe755a0..dac36e9f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26703&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26703&range=00-01

  Stats: 14 lines in 1 file changed: 0 ins; 3 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/26703.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26703/head:pull/26703

PR: https://git.openjdk.org/jdk/pull/26703