Issue

Hi, The instructions to install OSRM on a Mac are out of date.
https://github.com/Project-OSRM/osrm-backend/wiki/Building-OSRM#os-x-enable_masonon
See the error below:

Steps to reproduce

➜  osrm-backend git:(master) ✗ ./third_party/mason/mason install cmake 3.6.2
zsh: no such file or directory: ./third_party/mason/mason

These instructions seem more up to date:
https://github.com/stanfordfuturebay/osrm-local#macos
https://gist.github.com/jyt109/76eba9b502e2c90bb728