HAVE_MKTEMP macro in addition to HAVE_MKSTEMP

returned by gethostname().

 unused variable

function to simply pass thru the key value, which is already a hash value.

mainly 4-byte hashes already, there is no locality-of-reference to exploit
as a Btree. About a 7% performance gain.

It must be specified on individual put() operations (and already is).

Plugged other small leaks.