$ gem install eventmachine Building native extensions. This could take a while... ERROR: Error installing eventmachine: ERROR: Failed to build gem native extension. /Users/nownabe/.anyenv/envs/rbenv/versions/2.2.2/bin/ruby -r ./siteconf20151127-59879-1tnovzf.rb extconf.rb checking for rb_trap_immediate in ruby.h,rubysig.h... no checking for rb_thread_blocking_region()... no checking for ruby/threa