envutil.rb: basename for diagnostic_reports
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57967 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
envutil.rb: basename for diagnostic_reports
report file uses base name only. [ci skip]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57967 b2dd03c8-39d4-4d8f-98ff-823fe69b080e