Normally, hash_finish() is declared as:
static inline uint32_t hash_finish(uint32_t hash, uint32_t final)

When __SSE4_2__ && __x86_64__, it is declared as:
static inline uint32_t hash_finish(uint64_t hash, uint64_t final)

A recent commit added an unneeded prototype in the first form, which caused
an error due to the redeclaration of a different type when the second form
was actually used.  This removes the prototype, fixing the problem.

It may not be a great idea to have two different forms for this function,
but it's long standing and so I don't want to change it immediately without
proper consideration.

Reported-by: "Fischetti, Antonio" <antonio.fischetti@intel.com>
Fixes: 67702b79

 ("hash: New helper functions for adding words in a buffer to a hash.")
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Darrell Ball <dlu998@gmail.com>