envutil.rb: diagnostic_reports for ruby-runner
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57656 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
envutil.rb: diagnostic_reports for ruby-runner
execs "RUBY_INSTALL_NAME" file, so search by that name.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57656 b2dd03c8-39d4-4d8f-98ff-823fe69b080e