Let provision script know FreeBSD
Let FreeBSD has its own build dir
Set flags for FreeBSD's compiler and linker
Gnu make under FreeBSD is gmake
$DISTRO will be used for C macro, truncate unnecessary part
Use `uname -s` to determine non-Linux platform
Add libraries and settings for FreeBSD
Include proper headers for FreeBSD
No utmpxname() under FreeBSD
No <uuid/uuid.h> under FreeBSD
Make room for FreeBSD events