Enable apache_benchmark mTCP SSL load test capability

[vincentmli]

Existing ab lack of SSL load test support. Add the apache benchmark
configure script with --enable-ssl and --with-ssl option. Adopt
openssl crypto/bio/bss_sock.c as example to enable ab to create SSL
connection over mTCP socket.

Example:

$./ab -N 1 -c 2 -n 4 https://10.1.72.68/
Configuration updated by mtcp_setconf().
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

---

Loading mtcp configuration from : config/mtcp.conf
Loading interface setting
EAL: Detected 16 lcore(s)
EAL: Detected 2 NUMA nodes
EAL: Auto-detected process type: PRIMARY
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Probing VFIO support...
EAL: PCI device 0000:0b:00.0 on NUMA socket -1
EAL: Invalid NUMA socket, default to 0
EAL: probe driver: 15ad:7b0 net_vmxnet3
Total number of attached devices: 1
Interface name: dpdk0
EAL: Auto-detected process type: PRIMARY
Configurations:
Number of CPU cores available: 1
Number of CPU cores to use: 1
Number of TX ring descriptor: 512
Number of RX ring descriptor: 0
Number of source ip to use: 0
Maximum number of concurrency per core: 16000
Maximum number of preallocated buffers per core: 16000
Receive buffer size: 8192
Send buffer size: 8192
TCP timeout seconds: 30
TCP timewait seconds: 0
NICs to print statistics: dpdk0

Interfaces:
name: dpdk0, ifindex: 0, hwaddr: 00:50:56:86:10:76, ipaddr: 10.1.72.28, netmask: 255.255.0.0
Number of NIC queues: 1

Loading routing configurations from : config/route.conf
Routes:
Destination: 10.1.0.0/16, Mask: 255.255.0.0, Masked: 10.1.0.0, Route: ifdx-0
Destination: 10.1.72.0/24, Mask: 255.255.255.0, Masked: 10.1.72.0, Route: ifdx-0
Destination: 10.2.72.0/24, Mask: 255.255.255.0, Masked: 10.2.72.0, Route: ifdx-0
Destination: 10.169.0.0/16, Mask: 255.255.0.0, Masked: 10.169.0.0, Route: ifdx-0

Loading ARP table from : config/arp.conf
ARP Table:
IP addr: 10.1.72.68, dst_hwaddr: 00:50:56:86:22:BA

Initializing port 0... Ethdev port_id=0 tx_queue_id=0, new added offloads 0x8011 must be within pre-queue offload capabilities 0x0 in rte_eth_tx_queue_setup()

done:
rte_eth_dev_flow_ctrl_get: Function not supported
[dpdk_load_module: 765] Failed to get flow control info!
rte_eth_dev_flow_ctrl_set: Function not supported
[dpdk_load_module: 772] Failed to set flow control info!: errno: -95

Checking link statusdone
Port 0 Link Up - speed 10000 Mbps - full-duplex
Benchmarking 10.1.72.68 (be patient)...
CPU0 connecting to port 443
CPU 0: initialization finished.
[mtcp_create_context:1359] CPU 0 is now the master thread.
[CPU 0] dpdk0 flows: 0, RX: 9(pps) (err: 0), 0.00(Gbps), TX: 0(pps), 0.00(Gbps)
[ ALL ] dpdk0 flows: 0, RX: 9(pps) (err: 0), 0.00(Gbps), TX: 0(pps), 0.00(Gbps)
rte_eth_stats_reset: Function not supported
..done

Server Software: BigIP
Server Hostname: 10.1.72.68
Server Port: 443
SSL/TLS Protocol: TLSv1.2,ECDHE-RSA-AES128-GCM-SHA256,2048,128

Document Path: /
Document Length: 13 bytes

Number of Cores: 1
Concurrency Level: 2
Time taken for tests: 0.715 seconds
Complete requests: 4
Failed requests: 0
Write errors: 0
Total transferred: 344 bytes
HTML transferred: 52 bytes
Requests per second: 5.60 [#/sec] (mean)
Time per request: 357.421 [ms] (mean)
Time per request: 178.710 [ms] (mean, across all concurrent requests)
Transfer rate: 0.47 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 5 7 1.2 7 8
Processing: 1 1 0.3 1 2
Waiting: 1 1 0.3 1 2
Total: 6 8 1.3 9 9

Percentage of the requests served within a certain time (ms)
50% 9
66% 9
75% 9
80% 9
90% 9
95% 9
98% 9
99% 9
100% 9 (longest request)
[RunMainLoop: 876] MTCP thread 0 finished.
[mtcp_free_context:1405] MTCP thread 0 joined.
[mtcp_destroy:1685] All MTCP threads are joined.