Add support for building jemalloc on SunOS

Change-Id: I1fc4bda7dcc5fecd88f86f7e6d15f56e9430dfc3
Reviewed-on: http://review.couchbase.org/44236
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>