[jdk11u-dev] RFR: 8287724: Fix various issues with msys2 [v2]

[George Adams]

> This is the final piece of the puzzle in order to backport the GitHub actions refactor

George Adams has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - merge master
 - Backport 2e21c87fac8d60c3c7ed7b2d0afae9abfc110359
 - win fixpath for makefile
 - Backport 764111ff831096729eb1bcc69a54d92fde67b044
 - Backport d29c78da19ba78214efe9e7856cde30fdd9ba8ab

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Changes: https://git.openjdk.org/jdk11u-dev/pull/1539/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1539&range=01
  Stats: 38 lines in 3 files changed: 23 ins; 7 del; 8 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1539.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1539/head:pull/1539

PR: https://git.openjdk.org/jdk11u-dev/pull/1539