fixed async udp client error.
fix swoole_async_write core dump on PHP7. Fixed swoole#501
use malloc_trim
fixed swoole#481.
fix websocker server lost 2 bytes.
disable swoole_http_client, Fix swoole#461
fix SWOOLE_KEEP connection leak.
concurrent Asynchronous mysql client
1.7.22 beta
fixed http_server memory leak in PHP7.