This reverts r58761 since fiddle is considered critical.
[ruby-core:81201] [ruby-core:81203]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58764 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
libffi is not installed on all systems, and is not needed
for most of the tests.
Tested on a fresh FreeBSD 11.0 VM
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58761 b2dd03c8-39d4-4d8f-98ff-823fe69b080e