Fixup r59961. Use http for libffi downloading.
A few environments couldn't handle https download. * https://rubyci.org/logs/mswinci.japaneast.cloudapp.azure.com/vc12-x64/ruby-trunk/log/20170919T032511Z.fail.html.gz * https://rubyci.org/logs/www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20170919T040500Z.fail.html.gz
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59964 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Added by hsbt (Hiroshi SHIBATA) about 8 years ago
Fixup r59961. Use http for libffi downloading.
A few environments couldn't handle https download.
* https://rubyci.org/logs/mswinci.japaneast.cloudapp.azure.com/vc12-x64/ruby-trunk/log/20170919T032511Z.fail.html.gz
* https://rubyci.org/logs/www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20170919T040500Z.fail.html.gz
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59964 b2dd03c8-39d4-4d8f-98ff-823fe69b080e