devel/ruby-build: 20150303 -> 20150506

Changelog: https://github.com/sstephenson/ruby-build/releases

• Add JRuby 1.7.20
• Add Rubinius 2.5.3
• Add JRuby 9.0.0.0.pre2
• Specify inet protocol
• Remove needless build flag for some 2.1 versions
• Update canonical MagLev 1.0.0 download location
• Ruby 2.0.0-p645
• Ruby 2.1.6
• Ruby 2.2.2
• Upgrade OpenSSL to 1.0.1m

PR: 199436
Submitted by: Koichiro IWAO <meta+ports@vmeta.jp> (maintainer)