Remove dependency on libcap
Remove dependency on libcap

Summary: looks like it is not used.

Test Plan: build mcrouter

Reviewed By: @int

Differential Revision: D2488691

fb-gh-sync-id: 393a6205f817ad14d90305f923645dc39c680a28

reddit/mcrouter,zhlong73/mcrouter,facebook/mcrouter,zhlong73/mcrouter,yqzhang/mcrouter,reddit/mcrouter,zhlong73/mcrouter,nvaller/mcrouter,synecdoche/mcrouter,nvaller/mcrouter,nvaller/mcrouter,facebook/mcrouter,synecdoche/mcrouter,reddit/mcrouter,nvaller/mcrouter,synecdoche/mcrouter,zhlong73/mcrouter,facebook/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,synecdoche/mcrouter,yqzhang/mcrouter,reddit/mcrouter,facebook/mcrouter