On the master branch, unittest does not pass with tsan

[bsergean]

https://travis-ci.org/machinezone/IXWebSocket/jobs/526045056

All the tests that are failing relates to ping/pong it seems.

[bsergean]

..../bin/sh: line 1:  2367 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_no_ping_but_timeout" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmphqOzfQWebsocket_no_ping_but_timeout.log" 2>&1
../bin/sh: line 1:  2374 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_ping_no_data_sent_setHeartBeatPeriod" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmp3mNQvyWebsocket_ping_no_data_sent_setHeartBeatPeriod.log" 2>&1
./bin/sh: line 1:  2376 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_ping_no_timeout" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmpfjdGBgWebsocket_ping_no_timeout.log" 2>&1
./bin/sh: line 1:  2382 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_ping_no_data_sent_setPingInterval" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmp_LL54XWebsocket_ping_no_data_sent_setPingInterval.log" 2>&1
./bin/sh: line 1:  2384 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_ping_timeout" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmpTnyIrKWebsocket_ping_timeout.log" 2>&1
../bin/sh: line 1:  2390 Abort trap: 6           "/Users/travis/build/machinezone/IXWebSocket/test/build/Darwin/ixwebsocket_unittest" "Websocket_ping_timeout_not_checked" > "/var/folders/nz/vv4_9tw56nv9k3tkvyszvwg80000gn/T/tmppeVDuqWebsocket_ping_timeout_not_checked.log" 2>&1