Revert "Try removing building C API specs in CRuby makefiles entirely"
This reverts commit 2a9236366d6016738a756caecab03263565a20c7. spec/ruby/optional/capi/spec_helper.rb doesn't work well for mingw.
Revert "Try removing building C API specs in CRuby makefiles entirely"
This reverts commit 2a9236366d6016738a756caecab03263565a20c7.
spec/ruby/optional/capi/spec_helper.rb doesn't work well for mingw.