Add App::cpm and fix slim builds for non-x86{,_64}

[zakame]

This adds a prebuilt version of https://metacpan.org/dist/App-cpm as an alternative CPAN module installer with full support for HTTPS sources (among other features such as described in https://metacpan.org/pod/App::cpm::Tutorial.)

Fixes #50.

This also includes a small fix for slim builds on non-x86 archs.

[waterkip]

Lgtm

[skaji]

• The self-contained cpm has the shebang #!/usr/bin/env perl. You may want to replace it by #!/usr/local/bin/perl.
• You may want to use "tag" url (not "main branch" url) to make the build process idempotent.
  Eg: https://raw.githubusercontent.com/skaji/cpm/0.997011/cpm

Thanks for using cpm 😊

[zakame]

@waterkip thanks for the review! 👍

@skaji yeah I was just about to ask you if it is fine to use the tagged version - as for the shebang, its already fine as is since $PATH is already set to look at /usr/local/bin first. Thanks for the feedback! 💯

[zakame]

Checks went well and a test cpm install even on slim is fast!

% time docker run --rm -it perl:5.36-slim cpm install Net::Async::HTTP
DONE install Module-Build-0.4231
DONE install Test-Refcount-0.10
DONE install Test-Identity-0.01
DONE install Struct-Dumb-0.12
DONE install URI-5.10
DONE install Future-0.48
DONE install Metrics-Any-0.07
DONE install IO-HTML-1.004
DONE install IO-Async-0.801
DONE install Test-Metrics-Any-0.01
DONE install Encode-Locale-1.05
DONE install LWP-MediaTypes-6.04
DONE install HTTP-Date-6.05
DONE install TimeDate-2.33
DONE install HTTP-Message-6.36
DONE install HTTP-Cookies-6.10
DONE install Net-Async-HTTP-0.48
17 distributions installed.
docker run --rm -it perl:5.36-slim cpm install Net::Async::HTTP  0.07s user 0.04s system 2% cpu 3.898 total

Will merge this in and get this released, thanks everyone! 🎉