Log Message:
Add patch to fix vulnerabilities of rubygems.

https://www.ruby-lang.org/en/news/2017/08/29/multiple-vulnerabilities-in-rubygems/

* a DNS request hijacking vulnerability
* an ANSI escape sequence vulnerability
* a DoS vulernerability in the query command
* a vulnerability in the gem installer that allowed a malicious gem to
  overwrite arbitrary files

Bump PKGREVISION.