dnf, jruby, and mock

[Ken Dreyer]

mock with dnf pulls in jruby to satisfy "Requires: ruby(release)" on
Rawhide. I've found that several (all?) of my local Rawhide mock
builds fail due to jruby issues. This makes maintaining gem packages
pretty tedious, and breaks fedora-review runs, etc.

Can we remove the "Provides: ruby(release)" from Fedora's jruby in
F23? That seems like it would be easier than switching all rubygem
packages that FTBFS to "Require: ruby-mri", and besides,  it often it
is not my noarch gem itself that breaks with jruby, but some other
build dependency somewhere in the chain. I think it makes sense to
just remove the virtual provide from jruby until jruby is more stable.

- Ken