Move glusterd.vol to glusterd.vol.sample.

This avoids the potential for overwriting a file that may have been
configured after the last install.
Use TCP transport by default, since it's always available.
Fix starting glusterd on FreeBSD.

- Pass in -p so that glusterd creates the pid file needed.
- Pre-create /var/run and /var/log directories/files required.
Fix calls to sys_lsetxattr() so they explicitly check for errors.

In the case of extattr_set_link(), it returns the number of bytes
written on success, and in any event both it and Linux/NetBSD
lsetxattr() specifically return -1 on error.