Dependency on serpent fails #10

Installing serpent 0.3.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/leeazzarello/.gem/ruby/2.5.1/gems/serpent-0.3.0/ext/serpent
/Users/leeazzarello/.rubies/ruby-2.5.1/bin/ruby -r ./siteconf20180418-78765-1rx97ar.rb extconf.rb
/Users/leeazzarello/.rubies/ruby-2.5.1/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require':
cannot load such file -- mkmf-rice (LoadError)
from /Users/leeazzarello/.rubies/ruby-2.5.1/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in
`require'
	from extconf.rb:2:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /Users/leeazzarello/.gem/ruby/2.5.1/gems/serpent-0.3.0 for inspection.
Results logged to
/Users/leeazzarello/.gem/ruby/2.5.1/extensions/x86_64-darwin-17/2.5.0-static/serpent-0.3.0/gem_make.out

An error occurred while installing serpent (0.3.0), and Bundler cannot continue.
Make sure that `gem install serpent -v '0.3.0'` succeeds before bundling.

In Gemfile:
  serpent

Unfortunately Rice does not build against a staticly linked Ruby.
You'll need to rebuild Ruby with --enable-shared to use this library.

If you're on rvm:   rvm reinstall [version] -- --enable-shared
If you're on rbenv: CONFIGURE_OPTS="--enable-shared" rbenv install [version]

If you are using Heroku, they use a own custom configured, staticly linked Ruby
for their stack and it unfortunately does not work with Rice. You will need to use
a custom Ruby build pack that builds and uses a non-static version of Ruby.

extconf failed, exit code 1

checking for -lserpent... no
missing libserpent.so
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/leeazzarello/.rubies/ruby-2.5.1/bin/$(RUBY_BASE_NAME)
	--with-libpath
	--without-libpath
	--with-serpentlib
	--without-serpentlib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Users/leeazzarello/.gem/ruby/2.5.1/extensions/x86_64-darwin-17/2.5.0/serpent-0.3.0/mkmf.log

extconf failed, exit code 1