cppclient: fix Windows build
cppclient: fix Windows build

Reviewed By: chadaustin

Differential Revision: D29561552

fbshipit-source-id: 4b29f4a7ad912dc21fd0bdf8b0eb688de9bdf7b3

nodakai/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman