build: drop support for VS 2013 in v6 LTS

[bnoordhuis]

This is split off from #7484 to discuss the possibility of dropping VS 2013 in v6 LTS. From the other issue:

Proposal: drop support for building node.js with VS 2013.

Motivation: VS 2013 has numerous bugs in its C++11 support and in general. The source tree is full of hacks that work around this broken compiler and pull requests sometimes strand on it (e.g. #5458.)

As to add-ons, we could extend VS 2013 support for our public headers for a while (and test that through test/addons) but V8 will probably force us to update the baseline there too. Chromium currently requires Visual Studio 2015 Update 2 so I expect V8 will follow suit sooner rather than later.

@joaocgreis reported in #7484 (comment):

I tested some of the most downloaded native modules (ws (to test bufferutil and utf-8-validate), node-sass, contextify, thread-sleep, weak, bcrypt, hiredis, sqlite3, v8-profiler, iconv, ref and v8-debug) using VS2013 and they all behave exactly the same whether node itself was built with VS2013 or VS2015.

So I think we should go ahead with this and start building v6 and v7 with VS2015.

Encouraging!

[jasnell]

Fwiw, I'm +1 on dropping support in v6

[ChALkeR]

+1 if this lands before LTS.

[orangemocha]

+1

[adron-orange]

Yes. Drop the support. Please +1.

[eljefedelrodeodeljefe]

+1 since otherwise big baggage for LTS (specifically) and mainstream development (in consequence).

[ChALkeR]

/cc @nodejs/platform-windows

[saghul]

+1

[cjihrig]

SGTM

[jasnell]

@nodejs/build ... what's the status of getting the CI updated to drop vs2013?

[joaocgreis]

@jasnell

• Release CI: Machines done, finetuning the job. Will let you know when it's ready to use.
• Test CI: Already compiles only with 2015 for the correct versions, but addons testing should still use VS2013 (next in my queue).
• CITGM: Stalled for now.

[MylesBorins]

@joaocgreis is there anything i can do to help with CITGM? We are not even building with windows ATM