use system rocksdb

This mostly just improves build times.

flake.nix

@@ -36,6 +36,10 @@
         sha256 = "sha256-8len3i8oTwJSOJZMosGGXHBL5BVuGQnWOT2St5YAUFU=";
       };
 
+      # Point to system RocksDB
+      ROCKSDB_INCLUDE_DIR = "${pkgs.rocksdb_6_23}/include";
+      ROCKSDB_LIB_DIR = "${pkgs.rocksdb_6_23}/lib";
+
       builder = (pkgs.callPackage naersk {
         inherit (toolchain) rustc cargo;
       }).buildPackage;
@@ -44,6 +48,9 @@
       packages.default = builder {
         src = ./.;
 
+        # Use system RocksDB
+        inherit ROCKSDB_INCLUDE_DIR ROCKSDB_LIB_DIR;
+
         nativeBuildInputs = (with pkgs.rustPlatform; [
           bindgenHook
         ]);
@@ -54,6 +61,9 @@
         # sources, and it can read this environment variable to do so
         RUST_SRC_PATH = "${toolchain.rust-src}/lib/rustlib/src/rust/library";
 
+        # Use system RocksDB
+        inherit ROCKSDB_INCLUDE_DIR ROCKSDB_LIB_DIR;
+
         # Development tools
         nativeBuildInputs = (with pkgs.rustPlatform; [
           bindgenHook