ruby: security bump to version 2.4.2

ruby: security bump to version 2.4.2

Fixed the following security issues:

CVE-2017-0898: Buffer underrun vulnerability in Kernel.sprintf
CVE-2017-10784: Escape sequence injection vulnerability in the Basic
authentication of WEBrick
CVE-2017-14033: Buffer underrun vulnerability in OpenSSL ASN1 decode
CVE-2017-14064: Heap exposure in generating JSON

For more details, see the release notes:
https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-4-2-released/

Drop now upstreamed rubygems patches and add hashes for the license files
while we're at it.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>