RFR: Merge jdk:master

[J.Duke]

Hi all,

this is an _automatically_ generated pull request to notify you that there are 58 commits from the branch
`jdk:master`that can **not** be merged into the branch `master`:

The following file contains merge conflicts:

- .jcheck/conf

All Committers in this [project](https://openjdk.java.net/census#Optional[panama]) have access to my [personal
fork](https://github.com/openjdk-bot/panama-foreign) and can therefore help resolve these merge conflicts (you may want
to coordinate who should do this). The following paragraphs will give an example on how to solve these merge conflicts
and push the resulting merge commit to this pull request. The below commands should be run in a local clone of your
[personal fork](https://wiki.openjdk.java.net/display/skara#Skara-Personalforks) of the
[openjdk/panama-foreign](https://github.com/openjdk/panama-foreign) repository.

# Ensure target branch is up to date
$ git checkout master
$ git pull https://github.com/openjdk/panama-foreign master

# Fetch and checkout the branch for this pull request
$ git fetch https://github.com/openjdk-bot/panama-foreign +53:openjdk-bot-53
$ git checkout openjdk-bot-53

# Merge the target branch
$ git merge master

When you have resolved the conflicts resulting from the `git merge` command above, run the following commands to create
a merge commit:

$ git add paths/to/files/with/conflicts
$ git commit -m 'Merge jdk:master'


When you have created the merge commit, run the following command to push the merge commit to this pull request:

$ git push https://github.com/openjdk-bot/panama-foreign openjdk-bot-53:53

_Note_: if you are using SSH to push commits to GitHub, then change the URL in the above `git push` command accordingly.

Thanks,
J. Duke

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

Commit messages:
 - 8253008: Remove develop flags TraceLongCompiles/LongCompileThreshold
 - 8253026: Remove dummy call to gc alot from VM Thread
 - 8243208: Clean up JVMFlag implementation
 - 8252406: Introduce Thread::as_Java_thread() convenience function
 - 8171303: sun/java2d/pipe/InterpolationQualityTest.java fails on Windows & Linux
 - 7183828: Invalid Image Variant when using anything other than BufferedImage
 - 8252817: Cleanup the classes in the java.awt.color package
 - 8252919: JDK built with --enable-cds=no fails with NoClassDefFoundError
 - 8252830: Correct missing javadoc comments in java.rmi module
 - 8252774: remove jdk.test.lib.FileInstaller action from graalunit tests
 - ... and 48 more: https://git.openjdk.java.net/panama-foreign/compare/e25f2a57...8777ded1

The webrev contains the conflicts with master:
 - merge conflicts: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=321&range=00.conflicts

Changes: https://git.openjdk.java.net/panama-foreign/pull/321/files
  Stats: 11470 lines in 469 files changed: 7120 ins; 1901 del; 2449 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/321.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/321/head:pull/321

PR: https://git.openjdk.java.net/panama-foreign/pull/321