Allow setting tags on reports

And generate index pages per tag.

TBBTestSuite/Reports.pm

@@ -108,12 +108,17 @@ sub make_reports_index {
     my @reports_by_time =
         sort { $reports{$b}->{time} <=> $reports{$a}->{time} } keys %reports;
     my %reports_by_tbbversion;
+    my %reports_by_tag;
     my %reports_by_type;
     foreach my $report (keys %reports) {
         my $tbbver = $reports{$report}->{options}{tbbversion};
         push @{$reports_by_tbbversion{$tbbver}}, $report if $tbbver;
         my $type = report_type($reports{$report});
         push @{$reports_by_type{$type}}, $report;
+        my $tags = $reports{$report}->{options}{tags} // [];
+        foreach my $tag (ref $tags ? @$tags : ($tags)) {
+            push @{$reports_by_tag{$type}->{$tag}}, $report;
+        }
         my $testsuite = $TBBTestSuite::Tests::testsuite_types{$type};
         $testsuite->{pre_reports_index}(\%reports, $reports{$report})
                 if $testsuite->{pre_reports_index};
@@ -143,6 +148,15 @@ sub make_reports_index {
             { %$vars, reports_list => \@s }, "index-$type.html")
                 || exit_error "Template Error:\n" . $template->error;
     }
+    foreach my $type (keys %reports_by_tag) {
+        foreach my $tag (keys %{$reports_by_tag{$type}}) {
+            my @s = sort { $reports{$b}->{time} <=> $reports{$a}->{time} }
+                @{$reports_by_tag{$type}->{$tag}};
+                $template->process("reports_index_$type.html",
+                    { %$vars, reports_list => \@s }, "index-$type-$tag.html")
+                        || exit_error "Template Error:\n" . $template->error;
+        }
+    }
 }
 
 sub text_report {