Fix uninitialized in this function error

Fix uninitialized in this function error

With some versions of gcc, n_buckets will be flagged as being uninitialized
before use.  While its technically impossible (since the switch statement,
even without a default, accounts for all possibilities), we'll initialize the
variable to 0 anyway.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@376457 65c4cc65-6c06-0410-ace0-fbb531ad65f3