Reduce debug output

because I found machine clock problem
see r67347
https://travis-ci.org/ruby/ruby/jobs/525784924
https://travis-ci.community/t/mtime-of-source-codes-are-sometimes-newer-than-build-time-clock-skew/3215

.travis.yml

@@ -412,16 +412,6 @@ before_script:
         # Debugging "Permission defined" failure on darwin like https://travis-ci.org/ruby/ruby/jobs/508683759
         set -x
         date
-        echo $USER
-        ls -la
-        ls -la .ext
-        ls -la .ext/common
-        ls -la .ext/common/bigdecimal
-        ls -la ext
-        ls -laR ext/bigdecimal
-        ls -la ../ext
-        ls -laR ../ext/bigdecimal
-        umask
         ./miniruby -e 'ARGV.map{[@1,File.stat(@1)]}.sort_by{@2.mtime}.each{p mtime:@2.mtime.to_f, ctime:@2.ctime.to_f, path:@1}' .ext/.timestamp/.RUBYCOMMONDIR*time .ext/common/bigdecimal/*.rb ../ext/bigdecimal/lib/bigdecimal/*.rb . .. .ext .ext/common .ext/common/bigdecimal ext/bigdecimal ../ext ../ext/bigdecimal ../ext/bigdecimal/lib ../ext/bigdecimal/lib/bigdecimal
       fi
       exit 1