Symbol not found _OBJC_CLASS_$_NSFont when requiring canvas

## Issue
I'm receiving this error while trying `require` node-canvas:

```
Error: dlopen(/Users/james/projects/audiogram/node_modules/canvas/build/Release/canvas.node, 1): Symbol not found: _OBJC_CLASS_$_NSFont
Referenced from: /Library/Frameworks/Mono.framework/Versions/4.8.1/lib/libpangocairo-1.0.0.dylib
Expected in: flat namespace
in /Library/Frameworks/Mono.framework/Versions/4.8.1/lib/libpangocairo-1.0.0.dylib
at Object.Module._extensions..node (module.js:598:18)
at Module.load (module.js:488:32)
at tryModuleLoad (module.js:447:12)
at Function.Module._load (module.js:439:3)
at Module.require (module.js:498:17)
at require (internal/module.js:20:19)
at Object. (/Users/james/projects/audiogram/node_modules/canvas/lib/bindings.js:3:18)
at Module._compile (module.js:571:32)
at Object.Module._extensions..js (module.js:580:10)
at Module.load (module.js:488:32)
```

## Steps to Reproduce

```js
require('canvas');
```

## Your Environment
* Version of node-canvas: ^1.6.5
* Environment: Node 7.8.0, npm 4.2.0, OSX 10.12.5