RFR: 8264425: Update building.md on non-English locales on Windows [v4]

[Magnus Ihse Bursie]

> Update the build documentation to reflect the fact that non-English locales are only supported on a "best effort" principle, and add instructions how to install the necessary language pack to Visual Studio.

Magnus Ihse Bursie has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'master' into readme-locale
 - Merge branch 'master' into readme-locale
 - * Add requirement on system locale as well.
   * Reorganize text to be more logical
   * Emphasize that the US locale should be used
 - Merge branch 'master' into readme-locale
 - Update wording according to review suggestion
 - 8264425: Update building.md on non-English locales on Windows

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Changes: https://git.openjdk.org/jdk/pull/16694/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16694&range=03
  Stats: 102 lines in 2 files changed: 96 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/16694.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16694/head:pull/16694

PR: https://git.openjdk.org/jdk/pull/16694