Backport of patch for bug#24471

mysql-test-run.pl:
    Removed "use diagnostics", reduces Perl speed significantly. Can be
    enabled with "perl -Mdiagnostics mysql-test-run.pl".
mtr_report.pl:
   Don't try output "skipped" comment if there is none (bug#24471)

mysql-test/lib/mtr_report.pl

@@ -94,10 +94,14 @@ sub mtr_report_test_skipped ($) {
   {
     print "[ disabled ]  $tinfo->{'comment'}\n";
   }
-  else
+  elsif ( $tinfo->{'comment'} )
   {
     print "[ skipped ]   $tinfo->{'comment'}\n";
   }
+  else
+  {
+    print "[ skipped ]\n";
+  }
 }
 
 sub mtr_report_tests_not_skipped_though_disabled ($) {

mysql-test/mysql-test-run.pl

@@ -66,7 +66,6 @@ use IO::Socket::INET;
 use Data::Dumper;
 use strict;
 use warnings;
-use diagnostics;
 
 select(STDOUT);
 $| = 1; # Automatically flush STDOUT