結論
CONFIGURE_OPTS
を設定した上で rbenv install
する。
具体例
$ CONFIGURE_OPTS="--with-readline-dir=/usr/local/opt --with-openssl-dir=/usr/local/opt" rbenv install 2.6.0 ruby-build: use openssl from homebrew Downloading ruby-2.6.0.tar.bz2... -> https://cache.ruby-lang.org/pub/ruby/2.6/ruby-2.6.0.tar.bz2 Installing ruby-2.6.0... ruby-build: use readline from homebrew Installed ruby-2.5.3 to /Users/FOOBAR/.rbenv/versions/2.6.0
$ pry [1] pry(main)>