e2mmap benchmark is not working (missing gem) in Ruby 3.0.x

[etagwerker]

Hi there,

At the moment this benchmark is not working:

➜  fast-ruby git:(master) ✗ ruby -v code/general/raise-vs-e2mmap.rb
ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-darwin20]
<internal:/Users/etagwerker/.rvm/rubies/ruby-3.0.2/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- e2mmap (LoadError)
	from <internal:/Users/etagwerker/.rvm/rubies/ruby-3.0.2/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from code/general/raise-vs-e2mmap.rb:2:in `<main>'

The solution would be to add this to the Gemfile:

gem 'e2mmap'

It seems that that benchmark might not be wanted in this project. After all, it is comparing Ruby vs. using the e2mmap gem. See: #95

I'm going to submit a PR removing that scenario, which should fix this issue. 😄