Fix CMake build related to index code refactor (#384)

Summary:
In d0139af, `block_cache/Index.cpp` was renamed to `block_cache/SparseMapIndex.cpp`, but this change was not reflected in the cmake build, causing errors.

Pull Request resolved: #384

Reviewed By: pbhandar2

Differential Revision: D74184037

Pulled By: haowu14

fbshipit-source-id: d0ce23fe7f85612ab1a1e7a6f929fa1ac0125273

Author: c8ef

cachelib/navy/CMakeLists.txt

@@ -25,10 +25,10 @@ add_library (cachelib_navy
   block_cache/BlockCache.cpp
   block_cache/FifoPolicy.cpp
   block_cache/HitsReinsertionPolicy.cpp
-  block_cache/Index.cpp
   block_cache/LruPolicy.cpp
   block_cache/Region.cpp
   block_cache/RegionManager.cpp
+  block_cache/SparseMapIndex.cpp
   common/Buffer.cpp
   common/Device.cpp
   common/FdpNvme.cpp