build for freebsd

× Add link directories
FreeBSD install non-base libraries into /usr/local/lib
× Only define XOPEN_SOURCE and others for linux
Hides some functions in FreeBSD
× Define _WITH_GETLINE
Required for getline() in FreeBSD
× Only use epoll() for Linux
Not available in FreeBSD
× Return value in hist_plugin_open()
Just a warning