add write_to_cache to descriptor

Signed-off-by: Jason Volk <jason@zemos.net>

src/database/engine/descriptor.rs

@@ -40,6 +40,7 @@ pub(crate) struct Descriptor {
 	pub(crate) bottommost_level: Option<i32>,
 	pub(crate) block_index_hashing: Option<bool>,
 	pub(crate) cache_shards: u32,
+	pub(crate) write_to_cache: bool,
 	pub(crate) auto_readahead_thresh: u32,
 	pub(crate) auto_readahead_init: usize,
 	pub(crate) auto_readahead_max: usize,
@@ -71,6 +72,7 @@ pub(crate) static BASE: Descriptor = Descriptor {
 	bottommost_level: Some(SENTINEL_COMPRESSION_LEVEL),
 	block_index_hashing: None,
 	cache_shards: 64,
+	write_to_cache: false,
 	auto_readahead_thresh: 0,
 	auto_readahead_init: 1024 * 16,
 	auto_readahead_max: 1024 * 1024 * 2,