MFC r298522:

The default value of MINFREE is defined to be 8% in
ufs/ffs/fs.h and not 10%. The newfs(8) and tunefs(8)
man pages had this change already, but fs(5) did not.
This change makes it consistent again.

Bump Dd.

PR: 204929
Submitted by: amutu@amutu.com
Sponsored by: Essen Linuxhotel Hackathon 2016