bundle installのmysql2 のエラー解決方法

【環境】
macOS Mojava
バージョン10.14.3

・ruby -v
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin18]

・rbenv versions
system
2.2.2
2.3.0
2.3.1

• 2.3.3 (set by /Users/ユーザー名/サイト名/.ruby-version)
  2.4.1
  2.5.3

mysql --version
/usr/local/opt/mysql@5.7/bin/mysql Ver 14.14 Distrib 5.7.25, for osx10.14 (x86_64) using EditLine wrapper

vi ~/.bash_profile

PATH=/usr/local/mysql/bin:$PATH
export PATH
export PATH="~/.rbenv/shims:/usr/local/bin:$PATH"
eval "$(rbenv init -)"

vi ~/.bashrc

alias mysql=/usr/local/opt/mysql@5.7/bin/mysql
alias mysqladmin=/usr/local/opt/mysql@5.7/bin/mysqladmin

【エラー内容】

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

Gem files will remain installed in
/Users/ユーザー名/サイト名/vendor/bundle/ruby/2.3.0/gems/mysql2-0.4.5 for
inspection.
Results logged to
/Users/ユーザー名/サイト名/vendor/bundle/ruby/2.3.0/extensions/x86_64-darwin-18/2.3.0-static/mysql2-0.4.5/gem_make.out

An error occurred while installing mysql2 (0.4.5), and Bundler cannot
continue.
Make sure that gem install mysql2 -v '0.4.5' --source 'https://rubygems.org/'
succeeds before bundling.

In Gemfile:
mysql2

---

---

【試した事】

・パスを通す
https://nekonenene.hatenablog.com/entry/2016/10/31/061350
の解決方法①

bundle config build.mysql2 --with-opt-lib=/usr/local/opt/openssl/lib --with-opt-include=-I/usr/local/opt/openssl/include

・インストール実行
gem install mysql2 -v '0.4.5' --source 'https://rubygems.org/'

▼エラー内容
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.

---

・gemfileのtherubyracerをコメントアウト

gem 'therubyracer'

---

・Xcodeの再インストール
xcode-select --install

▼エラー内容(インストール済)
xcode-select: error: command line tools are already installed, use "Software Update" to install updates