Ruby

compile.c: optimize unnecessary concatstrings

• compile.c (iseq_peephole_optimize): optimize away unnecessary
  concatenation of single string, following tostring which always
  puts a String instance.
  https://github.com/ruby/ruby/pull/1626#discussion_r139285653

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59945 b2dd03c8-39d4-4d8f-98ff-823fe69b080e