[jdk11u] RFR: Merge jdk11u-dev:master

[Christoph Langer]

Test-PR for Merging.

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Commit messages:
 - 8253424: Add support for running pre-submit testing using GitHub Actions
 - 8249095: tools/javac/launcher/SourceLauncherTest.java fails on Windows
 - 8209380: ARM: cleanup maybe-uninitialized and reorder compiler warnings
 - 8257913: Add more known library locations to simplify Linux cross-compilation
 - 8238930: problem list compiler/c2/Test8004741.java
 - 8254270: linux 32 bit build doesn't compile libjdwp/log_messages.c
 - 8269851: OperatingSystemMXBean getProcessCpuLoad reports incorrect process cpu usage in containers
 - 8212040: Compilation error due to wrong usage of NSPrintJobDispositionValue in mac10.12
 - 8263432: javac may report an invalid package/class clash on case insensitive filesystems
 - 8221988: add possibility to build with Visual Studio 2019
 - ... and 8 more: https://git.openjdk.java.net/jdk11u/compare/815d3e1c...1faefed2

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.java.net/jdk11u/pull/5/files
  Stats: 3081 lines in 40 files changed: 2829 ins; 197 del; 55 mod
  Patch: https://git.openjdk.java.net/jdk11u/pull/5.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u pull/5/head:pull/5

PR: https://git.openjdk.java.net/jdk11u/pull/5