Ffi-yajl 2.2.1 released

I just released ffi-yajl 2.2.1 to rubygems. This won’t be visible to
most users until we ship new chef and chef-dk artifacts that include
it. There are no functional or bugfixes in this version, other than
cleanup of warnings and code cleanup. I believe the circular argument
reference fixes will suppress some warnings for ruby 2.2.x users which
is likely the only end user impact.