Get mmap working with ruby 2.3.1

Gemfile

source "https://rubygems.org"

gem 'mmap', git: 'https://github.com/lyda/mmap.git', :branch => 'non-global-version'

run.sh

#! /bin/sh

test -f Gemfile.lock && rm Gemfile.lock
bundle install
bundle exec ruby test.rb

test.rb

require 'mmap'

mmap = Mmap.new(__FILE__)
mmap.advise(Mmap::MADV_SEQUENTIAL)

mmap.each do |line|
  puts line
end