Add double free protection to checkseapp.

A double free error occurs when building with non glibc
devices. The hdestroy() function frees all comparison
keys internally in these cases. So avoid an explicit
call to free().

Change-Id: If9c5dc1a969605cd1eeb9218de02a9f8dbbd3ae1
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>