meta: bump minimal supported Windows version

[refack]

Microsoft has announced that on January 14, 2020 it will end it's support for Windows 7 and Windows Server 2008 R2.

This semver-major PR bumps the stated minimal supported versions to Windows8.1/Server2012R2 so that we will be explicit with our support plan, and not state that we support and EOL platform for the next LTS node version.

As per:

node/BUILDING.md

Line 72 in 715df64

The community does not build or test against end-of-life distributions (EoL).

/CC @nodejs/platform-windows @nodejs/tsc

Refs: https://support.microsoft.com/en-us/help/4487594
Refs: https://support.microsoft.com/en-us/help/13853/windows-lifecycle-fact-sheet#section-2
Refs: nodejs/build#1663

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

@refack build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/2342/pipeline

[addaleax]

Question: Should we also bump the check in node_main.cc?

My guess is no, because we have no reason to believe that Node will definitely break on the newly unsupported platforms, but maybe I’m wrong about that?

[refack]

Question: Should we also bump the check in node_main.cc?

It's a good question. As I see it this PR is just a formal statement, we could relegate Windows 7 support to "experimental" as per:

node/BUILDING.md

Lines 66 to 68 in 715df64

	* **Experimental**: May not compile or test suite may not pass.
	These are often approaching Tier 2 support but are not quite ready.
	There is at least one individual providing maintenance.

[mcollina]

LGTM

[ChALkeR]

LGTM as a doc change.

[mhdawson]

@joaocgreis would be good to make sure you are comfortable with this as well.

[mhdawson]

LGTM

[bzoz]

We are currently investigating the issue, please give us some time. Marking as -1 so nobody lands this by accident.

[joaocgreis]

I am against this change at this moment, for the reasons detailed in nodejs/build#1663 (comment).

We should do this only when Windows 7/2008R2 actually reaches the EoL. Until then, this would be an invitation to remove CI or ignore results, and Windows 7/2008R2 still has many users. I don't see a reason to do this sooner.

[joaocgreis]

Opened #25838 to make it clear that we can remove Windows 7/2008R2 when it becomes EoL.

[BridgeAR]

@refack since #25838 landed and there are two -1 here, do you mind to close the PR?

[refack]

Stalled until 1.1.2020