RFR: Merge jdk:master

[J. Duke]

Hi all,

this is an _automatically_ generated pull request to notify you that there are 337 commits from the branch `jdk:master`that can **not** be merged into the branch `master`:

The following files contains merge conflicts:

- make/autoconf/flags-cflags.m4
- make/autoconf/toolchain.m4
- make/common/JdkNativeCompilation.gmk

All Committers in this [project](https://openjdk.org/census#mobile) have access to my [personal fork](https://github.com/openjdk-bots/mobile) 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.org/display/skara#Skara-Personalforks) of the [openjdk/mobile](https://github.com/openjdk/mobile) repository.


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

# Fetch and checkout the branch for this pull request
$ git fetch https://github.com/openjdk-bots/mobile.git +3:openjdk-bot-3
$ git checkout openjdk-bot-3

# 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-bots/mobile.git openjdk-bot-3:3


_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:
 - Merge jdk:master
 - 8244504: C2: refactor counted loop code in preparation for long counted loop
 - 8230827: javac gives inappropriate warning about potentially ambiguous methods
 - 8245786: Scope is wrong for ClassTree representing record
 - 8246027: Minimal fastdebug build broken after JDK-8245801
 - 8246034: Remove java.base/share/classes/jdk/internal/jrtfs/jrtfsviewer.js and java.base/share/classes/jdk/internal/jrtfs/jrtls.js
 - 8243936: NonWriteable system properties are actually writeable
 - Added tag jdk-15+25 for changeset 588330449887
 - 8245062: HtmlStyle: group and document members for nav, header, summary, details
 - 8245264: Test runtime/cds/appcds/SignedJar.java fails
 - ... and 71 more: https://git.openjdk.org/mobile/compare/44bde0d0...c38f0064

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=mobile&pr=23&range=00.0
 - jdk:master: https://webrevs.openjdk.org/?repo=mobile&pr=23&range=00.1

Changes: https://git.openjdk.org/mobile/pull/23/files
  Stats: 131113 lines in 1288 files changed: 58777 ins; 66629 del; 5707 mod
  Patch: https://git.openjdk.org/mobile/pull/23.diff
  Fetch: git fetch https://git.openjdk.org/mobile.git pull/23/head:pull/23

PR: https://git.openjdk.org/mobile/pull/23