add simply perf test using 'ab'

bin/test/perftest2.pl

+#!/usr/bin/perl -w
+
+use lib '../../';
+use strict;
+use Time::HiRes qw( usleep ualarm gettimeofday tv_interval );
+use PVE::INotify;
+use PVE::AccessControl;
+
+my $hostname = PVE::INotify::read_file("hostname");
+
+# normally you use username/password,
+# but we can simply create a ticket if we are root
+my $ticket = PVE::AccessControl::assemble_ticket('root@pam');
+
+
+my $cmd = "ab -c 2 -n 1000 -C 'PVEAuthCookie=$ticket'  https://$hostname:8006/api2/json";
+print "$cmd\n";
+system($cmd) == 0 || die "command failed - $!\n";