fatal error: core.h: No such file or directory breaks build against node 10.2.0

[mkrufky]

node 10.1.0 was fine, but 10.2.0 introduced this new fatal error:

mk@vujade:~/git/nan$ npm run rebuild-tests 

> [email protected] rebuild-tests /home/mk/git/nan
> node-gyp rebuild --msvs_version=2015 --directory test

make: Entering directory '/home/mk/git/nan/test/build'
  CXX(target) Release/obj.target/accessors/cpp/accessors.o
In file included from ../../nan.h:51:0,
                 from ../cpp/accessors.cpp:9:
/home/mk/.node-gyp/10.2.0/include/node/node.h:53:10: fatal error: core.h: No such file or directory
 #include "core.h"  // NOLINT(build/include_order)
          ^~~~~~~~
compilation terminated.

I first noticed this in CI:
https://travis-ci.org/mkrufky/node-dvbtee/jobs/382993499

...and then I was able to easily reproduce it locally after upgrading node from v10.1.0 to v10.2.0

Oops, this is a node bug, and not NAN's issue: nodejs/node#20921

Will likely end up closing this soon.

[mkrufky]

Closing this now -- a fix for it landed upstream in nodejs/node@3f4caec. A 10.2.1 release with that fix should follow shortly. No changes to NAN or any native modules are necessary.