[IR] Bugfix setting up zsuper localvar call args

* This bug (now fixed) only kicked in when local var accesses aren't
  converted to lvar load/store instructions. For example, when run
  with only basic passes enabled on the following code.

$ jruby -Xir.passes=OptimizeTempVars,LinearizeCFG foo.rb
$ cat foo.rb
class Base
  def attr_accessor(*); puts "IN BASE VERSION"; end
  def no_commands; yield; end
end

class AppBase < Base
  def attr_accessor(*); no_commands { super }; end
end

AppBase.new.attr_accessor(1,2)