Install base-devel in container.
image: "archlinuxjp/archlinux"
before_script:
-- pacman -Sy --noconfirm neovim python-{neovim,pytest} git rustup
+- pacman -Sy --noconfirm neovim python-{neovim,pytest} git rustup base-devel
- git clone https://github.com/jonathandturner/rls /opt/rls
- rustup default nightly
