devel/node-gyp: Add port

[otis]

Summary

Add node-gyp, a build frmework for building Node.js applications.
It will be used for node-re2 that will be used for upcoming
textproc/kibana7 update.

[osa]

Thanks for creating the port for this.

We'd definitely need to notify @sunpoet and @bhughes about this to avoid a potential conflict with packages, because www/npm also installs the following files:

@(,,755) lib/node_modules/npm/bin/node-gyp-bin/node-gyp
lib/node_modules/npm/bin/node-gyp-bin/node-gyp.cmd

[osa]

LGTM.