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

If --with-jemalloc option is not specified, then it defaults to tcmalloc.

If --with-jemalloc is specified, then --without-tcmalloc is required.
Also if a rocksdb static linking is desired --with-librocksdb-static,
do not use --with-jemalloc, as rocksdb uses tcmalloc for builds.

Support for jemalloc in package build and perf stats/heap profiler is
underway

Signed-off-by: shishir gowda <shishir.gowda@sandisk.com>
is this line needed?