RFR: 8281384: Random chars on paste from Windows clipboard [v8]

[Oliver Schmidtmer]

> Windows programs may reuse a clipboard buffer that is larger than the new content. In this case de NUL terminator is not at the end of the buffer, but within it. 
> The current implementation copys the whole buffer into a text field, including the NUL terminator and the remaining chars.
> 
> The JIRA ticket contains a JNA based sample program, which prefills the buffer for demonstrating this issue.
> If this should be added as a unit test, I'm open for advice how to do that.

Oliver Schmidtmer has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains nine additional commits since the last revision:

 - revert to original mime types
 - Merge remote-tracking branch 'remotes/origin/master' into JDK-8281384
 - readding flavors with changed mapping
 - remove non unicode textformats
 - format and unneeded var removed
 - cleanup
 - search NUL terminator in native code
 - check both UTF16 bytes
 - JDK-8281384: Random chars on paste from Windows clipboard

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1724/files
  - new: https://git.openjdk.org/jfx/pull/1724/files/7330b8da..3a4eb33a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1724&range=07
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1724&range=06-07

  Stats: 6079 lines in 106 files changed: 4047 ins; 1426 del; 606 mod
  Patch: https://git.openjdk.org/jfx/pull/1724.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1724/head:pull/1724

PR: https://git.openjdk.org/jfx/pull/1724