[jdk11u-dev] RFR: 8220445: Support for side by side MSVC Toolset versions

[Christoph Langer]

This is a backport of JDK-8220445 Support for side by side MSVC Toolset versions. It is needed to support the GitHub Actions workflow for Windows because it is using the hereby introduced configure option --with-msvc-toolset-version.

The backport did not apply cleanly because JDK-8215445: Enable building for Windows in WSL is missing. I adapted the change to make it fit.

I moved the line
`        $ECHO "$WINPATH_BASH -c 'echo VCToolsRedistDir="'"$VCToolsRedistDir " >> set-vs-env.sh' \
            >> $EXTRACT_VC_ENV_BAT_FILE`
to the fitting place and dropped the hunk
`        $ECHO 'echo VCToolsRedistDir="%VCToolsRedistDir% " >> set-vs-env.sh' \
            >> $EXTRACT_VC_ENV_BAT_FILE`

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Commit messages:
 - 8220445: Support for side by side MSVC Toolset versions

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/180/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=180&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8220445
  Stats: 24 lines in 1 file changed: 22 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/180.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/180/head:pull/180

PR: https://git.openjdk.java.net/jdk11u-dev/pull/180