Prototype warning cleanup - big endian

Prototype warning cleanup - big endian

Move function definitions above their use in quad_cksum.c and
remove the (incomplete) prototypes.

Clears up a few warnings on big endian systems.

Change-Id: Id860f904fff9fb033ee4b2032162304a4af7423a
Reviewed-on: http://gerrit.openafs.org/2601
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit de341580a6003944f1ae4b01c56bf483ead857d1)
Reviewed-on: http://gerrit.openafs.org/2669