* lib/rake/cpu_counter.rb (count): prefer Etc.nprocessors, which
is hundreds times faster.
* test/rake/test_rake_cpu_counter.rb: add tests for features, and
remove useless tests.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48127 b2dd03c8-39d4-4d8f-98ff-823fe69b080e