Change the type of sysvar rocksdb_delayed_write_rate from unsigned long long
to uint64_t to match the type of rocksdb::DBOptions::delayed_write_rate.
Remove the MyRocks layer source code variable and bind the sysvar directly to
the RocksDB var.
Change the types of rocksdb_compaction_sequential_deletes &
rocksdb_compaction_sequential_deletes_window (both sysvars and source code
variables) from long long to uint64_t to match the field types in
Rdb_compact_params, drop the redundant casts. Leave
rocksdb_compaction_sequential_deletes_file_size unchanged because it has an
additional -1 value as a sysvar.
Change the type of rocksdb_max_bottom_pri_background_compactions source code
variable from uint32_t to int and sysvar from uint to int because this is what
the API expects. Change also the type of
ROCKSDB_MAX_BOTTOM_PRI_BACKGROUND_COMPACTIONS and parameter type of
rocksdb_set_max_bottom_pri_background_compactions_internal accordingly.