node-gyp: support for Chromium versions of Python

[hashseed]

V8's test infrastructure uses a particular brand of Python. We have been floating this fix on our Node.js branch for quite a while. I am hoping that we can land this upstream too.

Checklist

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

[nodejs-github-bot]

@hashseed build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/261/pipeline

[richardlau]

This should be upstreamed to https://github.com/nodejs/node-gyp otherwise it's likely to be lost on npm updates.

[Trott]

Whether floating the patch here or upstreaming, might it be better to replace the code block added in this PR and the two similar indexOf()/.replace() things above with something like this (untested) block?:

var matches = version.match(/(\d+\.\d+\.\d+)/);
if (!matches) {
  return this.callback(new Error('unexpected version string format: ' + version));
}
if (version !== matches[0]) {
  this.log.silly('stripping characters from version: "' + version + '" -> "' + matches[0] + '"');
  version = matches[0];
}

[Trott]

@nodejs/node-gyp

[hashseed]

I created a PR for nodejs/node-gyp.