Fix incorrect flag set

Author: dudoslav

CMakeLists.txt

@@ -16,13 +16,14 @@ find_package(pybind11 CONFIG REQUIRED)
 set(TileDB_DIR $ENV{TILEDB_PATH})
 find_package(TileDB)
 if (NOT TileDB_FOUND)
+    message(STATUS "TileDB library not found, downloading...")
     include(cmake/DownloadTileDB.cmake)
     fetch_prebuilt_tiledb(
             VERSION 2.23.0
             RELLIST_HASH SHA256=2221b0ee2af2675d69f9cb31bc22062d3f379eeecc83b5fc713d00fa03d6e56f
     )
     find_package(TileDB REQUIRED)
-    set(TILEDB_DOWNLOADED)
+    set(TILEDB_DOWNLOADED "True")
 endif()
 
 add_subdirectory(tiledb)