Ever since [JDK-8257679](https://bugs.openjdk.java.net/browse/JDK-8257679) was merged in 16, MSys 2 became capable of building a functional JDK on Windows. This PR updates some outdated documentation in building.html and building.md to reflect that change.
I appreciate any reviews, and would like to know how I might be able to improve the wording of both updated docs, if possible. ------------- Commit messages: - Update documentation to mention MSys 2 support Changes: https://git.openjdk.java.net/jdk/pull/7242/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7242&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8257679 Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod Patch: https://git.openjdk.java.net/jdk/pull/7242.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/7242/head:pull/7242 PR: https://git.openjdk.java.net/jdk/pull/7242
