hashtable: consistently use Duplicate/Dealloc template allocators
hashtable: consistently use Duplicate/Dealloc template allocators

Necessary for apps using these templates to be able to use custom
allocators like jemalloc, which may override malloc/free.

Signed-off-by: Steven Noonan <4068f0880b399410602d694b3cc711c8a8f4727e@uplinklabs.net>

tycho/crisscross,tycho/crisscross,tycho/crisscross