Fix a segfault when an allocator is unused (i.e. no allocations) and we try to free it.
Fix a segfault when an allocator is unused (i.e. no allocations) and we try to
free it.

* buckets/allocator.c
  (cleanup_allocator): If we never allocated anything, don't try to free NULL.


git-svn-id: 683495cb1553624b05a54e2ba9533425f69cf277@933 61a7d7f5-40b7-0310-9c16-bb0ea8cb1845

coapp-packages/serf,coapp-packages/serf,coapp-packages/serf