Import of OpenBSD's sys/sys/hash.h providing generic 32bit hash functions.
Import of OpenBSD's sys/sys/hash.h providing generic 32bit hash functions.

Requested by:	flz (to port Open[BGP|OSPF]D)
MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase