Fix data race in WebSocket where _url is accessed without protection in setThreadName

Also fix with url usage + docker container uses fedora and works with tsan

test/CMakeLists.txt

@@ -8,6 +8,9 @@ project (ixwebsocket_unittest)
 set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/../third_party/sanitizers-cmake/cmake" ${CMAKE_MODULE_PATH})
 find_package(Sanitizers)
 
+# set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=thread")
+# set(CMAKE_LD_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=thread")
+
 set (CMAKE_CXX_STANDARD 14)
 
 if (NOT WIN32)