Add missing grep and awk dependencies for pacman

[alyssais]

The default Arch Docker image doesn't have these installed.

Reproduction:

FROM archlinux/base

RUN pacman -Syu --noconfirm sudo make && \
    curl -Lo ruby-install-master.tar.gz https://github.com/postmodern/ruby-install/archive/master.tar.gz && \
    tar -xzvf ruby-install-master.tar.gz && \
    cd ruby-install-master && \
    make install && \
    pacman -Syu --noconfirm grep awk && \
    yes | ruby-install ruby

[postmodern]

@alyssais should these dependencies be added to any other rubies that compile?

[postmodern]

@alyssais also, is this an issue that should be fixed in the Arch Docker image, or is it intentionally bare bones?

[alyssais]

@alyssais should these dependencies be added to any other rubies that compile?

No other ruby that compiles seems to need these. Rubinius seems like it would, but doesn't compile anyway, I think because Arch's clang is too new (and it doesn't offer older versions).

@alyssais also, is this an issue that should be fixed in the Arch Docker image, or is it intentionally bare bones?

I assume it must be intentional -- it would be very difficult for it to be accidental because of how obvious it is, since almost nothing works. ;)

[postmodern]

We could add awk, but ruby-install uses grep internally before it even gets to installing dependencies, so that wouldn't work.

Also, ruby-install is not necessarily needed to install a ruby into a docker image. It's probably easier to add the commands to install the dependencies, download the .tar.xz archive, extract, ./configure --prefix=... && make && make install.