Don't crash on failed connection
Don't crash on failed connection

Summary: Fixes a crash where socket_ was freed following a failure to connect, causing
a subsequent attempt to access AsyncSocket::getFD to segfault.

Test Plan: automated tests

Reviewed By: @andreazevedo

Differential Revision: D2134379
zhlong73/mcrouter,leitao/mcrouter,yqzhang/mcrouter,easyfmxu/mcrouter,is00hcw/mcrouter,leitao/mcrouter,facebook/mcrouter,zhlong73/mcrouter,is00hcw/mcrouter,glensc/mcrouter,reddit/mcrouter,synecdoche/mcrouter,leitao/mcrouter,zhlong73/mcrouter,reddit/mcrouter,zhlong73/mcrouter,nvaller/mcrouter,glensc/mcrouter,evertrue/mcrouter,synecdoche/mcrouter,tempbottle/mcrouter,is00hcw/mcrouter,tempbottle/mcrouter,facebook/mcrouter,reddit/mcrouter,glensc/mcrouter,is00hcw/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,nvaller/mcrouter,nvaller/mcrouter,nvaller/mcrouter,synecdoche/mcrouter,easyfmxu/mcrouter,facebook/mcrouter,easyfmxu/mcrouter,tempbottle/mcrouter,yqzhang/mcrouter,reddit/mcrouter,evertrue/mcrouter,easyfmxu/mcrouter,synecdoche/mcrouter,leitao/mcrouter,evertrue/mcrouter,facebook/mcrouter,tempbottle/mcrouter,evertrue/mcrouter,glensc/mcrouter