adding formula for glbinding

see https://github.com/hpicgs/glbinding
You mean like so:
```
system ENV.cxx, "-o", "test", "test.cpp", "-std=c++11", "-stdlib=libc++", "-I#{include}/glbinding", "-I#{lib}/glbinding", "-lglbinding", *(ENV.cflags.to_s.split)
```

I don't like that, to be honest, since it just is a very long line of code. And splitting it up into multiple lines gets a down-vote from ```brew audit``` – since I'd need to add trailing whitespaces to keep it readable like so:

```
system ENV.cxx, "-o", "test", "test.cpp", "-std=c++11", "-stdlib=libc++",
                "-I#{include}/glbinding", "-I#{lib}/glbinding",
                "-lglbinding", *(ENV.cflags.to_s.split)
```