Kick the hash_slinger interface around a bit:

Isolate more stuff in hash_slinger.h.

Remove hash_slinger from cache.h, include in .c's as necessary.

Save a malloc per objhead by putting a few fields into the objhead
for the hash_slingers to use.

Preinitialize the refcount when we precreate the objhead.

Move the hash-string allocation into HSH_Copy(), no point in
duplication of mandatory step.



git-svn-id: http://www.varnish-cache.org/svn/branches/2.0@3615 d4fa192b-c00b-0410-8231-f00ffab90ce4