MB-9525: Enable use of tcmalloc for all platforms

I've experienced that using tcmalloc from homebrew may cause
the process to crash during loading of libraries, but others
have had success.

Change-Id: I0aabf0995ab31d167c1f17068c8590f60a8259ac
Reviewed-on: http://review.couchbase.org/30310
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>