[chef] ffi-yajl 2.2.1 released

[Lamont Granquist < >]

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.

https://github.com/chef/ffi-yajl/blob/master/CHANGELOG.md#221-07132015