Log message:
ruby-mini_portile2: update to 2.4.0.

Upstream changes (from CHANGELOG.md):

### 2.4.0 / 2018-12-02

#### Enhancements

* Skip progress report when Content-Length is unavailable. [#85] (Thanks, @eagletmt!)

Log message:
misc/ruby-mini_portile2: update to 2.3.0

### 2.2.1 / 2017-09-13

#### Enhancements

* Verify checksums of files at extraction time (in addition to at download \ 
time). (#56)
* Clarify error message if a `tar` command can't be found. (#81)

Log message:
Update ruby-mini_portile2 to 2.2.0.

### 2.2.0 / 2017-06-04

#### Enhancements

* Remove MD5 hashing of configure options, not avialbale in FIPS mode. (#78)
* Add experimental support for cmake-based projects.
* Retry on HTTP failures during downloads. [#63] (Thanks, @jtarchie and @jvshahid!)
* Support Ruby 2.4 frozen string literals.
* Support applying patches for users with misconfigured git worktree. [#69]
* Support gpg signature verification of download resources.

Log message:
Import ruby-mini_portile2-2.1.0 as misc/ruby-portile2.

Note ruby-mini_portile2 is updated and renamed version of
ruby-mini_portile by the upstream due to backwards-incompatible
behavioral changes from mini_portile 0.7.0.rc* and prior.

This project is a minimalistic implementation of a port/recipe system
for developers.
Because "Works on my machine" is unacceptable for a library maintainer.