add the leveldb/libleveldb.a and leveldb/libmemenv.a

Signed-off-by: spark.huang <240401736@qq.com>
delete the leveldb code

Signed-off-by: spark.huang <240401736@qq.com>
modify the Makefile to use the leveldb.a

Signed-off-by: spark.huang <240401736@qq.com>