KUDU-1998. Re-enable tcmalloc on OSX
KUDU-1998. Re-enable tcmalloc on OSX

We switched back away from using malloc hooks for memory tracking, so
this shouldn't be an issue anymore.

Change-Id: I9bb3329aa4c12595dedf27d022558671e90206fb
Reviewed-on: http://gerrit.cloudera.org:8080/6917
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Tested-by: Kudu Jenkins

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