SITEDIR reference in options.rb

[mpapis]

https://github.com/rdoc/rdoc/blob/master/lib/rdoc/options.rb#L931 references SITEDIR which was removed in 8d34bb5#L1L20

Forwarding from rvm/rvm#1583

[drbrain]

Fixed by @729b62a8

[stomar]

@drbrain Could you fix this in ruby-trunk and the 2.0.0 branch?

With rvm, I always need to install each ruby twice, since with the standard install the ri core documentation is missing. :(

[stomar]

@drbrain

Now fixed in trunk, see https://github.com/ruby/ruby/blob/trunk/lib/rdoc/options.rb#L958.
But this bug is still present in 2_0_0 branch: https://github.com/ruby/ruby/blob/ruby_2_0_0/lib/rdoc/options.rb#L919

Could you please backport?

[stomar]

@drbrain Any chance this gets backported to 2_0_0 before next patchlevel release?