bundle install 時、mysql2でエラー - Qiita$ sw_vers ProductName: Mac OS X ProductVersion: 10.14.2 $ ruby -v ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17] $ rails -v Rails 5.1.2 Gem::Ext::BuildError: ERROR: Failed to build gem native extension. current directory: /Users/{username}/rails_app/test-mysql/vendor/bundle/gems/mysql2-0.5.2/ext/mysql2 /Users/{username}/.rbenv/versions/2.5.1/bin/ruby -I /Users/{username}/.rbenv/versio
