This patch adds a TOYBOX_SELINUX configuration option to control both the SELinux commands (such as chcon) and the SELinux-specific options to regular commands (such as ls -Z). This lets us #include <selinux/selinux.h> in portability.h. I've also fixed chcon to insist on being given the a context argument. This patch also adds -Z to id and fixes id's regular output (-G should be separated by spaces, non-G output should be separated by commas, and you don't want a double comma where the egid is omitted from the list of groups).