Added fix for building node 10 - #48

Only relevant for 10 yea? Should prob only enable it there

Yes only relevant for 10 AFAIK, sure I can add a version check for this condition

//Edit: Short background for this: I have a N-API module that needs at least N-API v5, so I build explicitly against node v10.17.0 and ended up with that bug

It looks like the flag has been removed in node 15: nodejs/node#27576. The default value in node was the same as the value we set here with --build_v8_with_gn=false, so it should not affect node 10-14.

I can add a version check for this condition

👍 Better to be safe than sorry, and it'll remind us to remove it in the future.

Closes #10

I added a version check for 10 and 11 only because I had no issues with other node versions.

Travis is taking too long, I'm canceling.

4.1.1