add a node suffix to V8's version number

[targos]

About one year ago, we tried to add the possibility on V8 to have a custom suffix appended to the version string. This would allow us to apply patches to stable V8 versions without conflicting with the original version number and keep track of our own changes. The idea is to define this suffix in common.gypi (example).
For example we can choose to use .node.X or -node.X and increment X every time we apply a non-official patch to deps/v8. The full version string would look like 6.1.534.42.node.12.

Unfortunately, the change failed to land at that time because of an issue with how V8 is updated in Chromium. I changed the code a little bit this week and it should be good to go. The CL has already been reviewed and accepted: https://chromium-review.googlesource.com/c/v8/v8/+/690475

@nodejs/v8 and @nodejs/tsc please give your opinion on the approach. If you are OK with it, I will land the change in V8 and backport it here so we can have it on time for v9.0.0.

[mcollina]

This is a very good idea.

[addaleax]

Thanks for looking after this – I think I’d prefer -node.X as the suffix :)

[ofrobots]

Thanks for getting this put together! I think this would be semver major because I suspect people try to parse the process.versions.v8 string.

[targos]

I think this would be semver major because I suspect people try to parse the process.versions.v8 string.

I agree. This is why I would like it to be ready for v9.

[targos]

PR: #15785