modules: adding load linked modules feature

[thlorenz]

refiling PR from node-fwd

• introduced NM_F_LINKED flag to identify linked modules
• setting node_is_initialized after calling V8::Initialize in order to
  make the right decision during initial module registration
• introduced modlist_linked in order to track modules that were
  pre-registered in order to complete it once node is initialized
• completing registration of linked module similarly to the way it's
  done inside DLOpen

[bnoordhuis]

For the record, I already LGTM'd this but I'd like @trevnorris to sign off on it.

[trevnorris]

LGTM

[rvagg]

running full CI on this https://jenkins-node-forward.nodesource.com/job/iojs+any-pr+multi/3/

[rvagg]

@thlorenz would it be difficult to add a simple test for this in test/addons/ and perhaps a super-simple sanity check in test/simple/? seems like something that's ripe for regressions.

[thlorenz]

Ideally yes, but that would require adding something to node.gyp the way nad does.
That would also mean we'd have to recompile to run it.

So I think it'd have to be some integration test, possibly even executed manually, not sure.

Not sure when I can get to it. Could we merge this anyhow and I'll think about how to best do this and supply tests in another PR?

[trevnorris]

I'd normally require a test, but since the API is technically "private" (done, IMO, so the API can be hashed out as it's used if necessary) there's no need for a test at the moment.

[thlorenz]

Thanks @trevnorris and as I said it won't be a simple test.
Will hash out with @rvagg how to best include and run these integrationy tests in general and add one for this at that point.

[rvagg]

@thlorenz I assumed that the test/addons/ directory would be the place for this--they are a separate test run and are all compiled and loaded to test, perhaps we could do something similar to make this testable?

[thlorenz]

No this doesn't work exactly like an addon. It's a linked module, i.e. it has to be made part of the code base by modifying the node.gyp file (what nad does).

[rvagg]

this got landed in joyent/node didn't it? should we land it here or close and wait for the next pull from joyent/node?

[thlorenz]

It did land in joyent/node as well but in different shape since things were adapted to older API, i.e. env->SET_MODULE was not available there.

[rvagg]

landed via f4e058d