Patch for linking jemalloc into mysqld

The jemalloc library is able to manage memory for TokuDB a lot better than the lib mallocator with respect to keeping the mysqld RSS under control. Tokutek shipped a product that used LD_PRELOAD to preload the jemalloc library into mysqld in the mysqld_safe script. Unfortunately, this solution proved to be brittle and a lot of customers ended up running mysqld directly, and blew up their systems as the libc mallocator could not keep the mysqld RSS under control.

Tokutek now links jemalloc into mysqld.