dpkg moved to away from dynamically allocating the hashtables in commit
c87339d584 (dpkg: trivial code shrinkage, and redo G trick correctly) almost
ten years ago, but the cleanup code was never adjusted to match.
Glibc loudly complains about this:
*** Error in `dpkg': free(): invalid pointer: 0x0000007fac3478c0 ***
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>