Build: Allow jemalloc enabled build with rocksdb-static
Presently, we can't do jemalloc enabled OSD build along with
rocksdb-static.Rocksdb is now mandatory with Bluestore and that's why
jemalloc builds are failing. Sometimes back the following commit
fd7a35731854528dde10deb3444a82ae4c1a9206 is introduced to build rocksdb
with jemalloc as well, so, we can allow jemalloc build along with
rocksdb-static now. Removing the redundant check from configure.ac.
Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>