Jemalloc-support: Added --with-jemalloc configure option

Selecting jemalloc, prevents static linking of rocksdb, as it
is dependent on tcmalloc. Default option remains tcmalloc.
Package build builds with tcmalloc support. Support for 
jemalloc in package build and perf stats/heap profiler is 
underway.

Signed-off-by: shishir gowda <shishir.gowda@sandisk.com>
Currently rocksdb is built with tcmalloc by default, and statically linked as ceph key-value store. Hence disabling static build of rocksdb, and supporting only dynamic linking of rocksdb