r281955 removed M_FLOWID which could cause problems for old drivers still using
the field. It cannot be removed from stable/10 so restore it.

Change M_HASHTYPE_GET() and M_HASHTYPE_SET() to do the right thing when M_FLOWID
exists.

Also bumping the FreeBSD version to note the fact that M_FLOWID is brought back
in stable/10.
(Just a note that M_FLOWID has been removed from -head.)

Spotted by: np
Suggested by: hans
Reviewed by: hans, tuexen (earlier version)
Helped by: jhb, delphij, gjb
Sponsored by: Limelight Networks