change Builder#run base class method to new signature

spec/rscons/builder_spec.rb

@@ -2,7 +2,7 @@ module Rscons
   describe Builder do
     describe "#run" do
       it "raises an error if called directly and not through a subclass" do
-        expect{subject.run(:target, :sources, :cache, :env, :vars)}.to raise_error /This method must be overridden in a subclass/
+        expect{subject.run({})}.to raise_error /This method must be overridden in a subclass/
       end
     end
   end