Add a couple of TODOs into related code

Noticed while refactoring

Author: dcoutts

src/Database/LSMTree/Internal/CRC32C.hs

@@ -13,6 +13,7 @@
 -- * Support for verifying checksums of files.
 -- * Support for a text file format listing file checksums.
 --
+-- TODO: specialise all the functions here to IO
 module Database.LSMTree.Internal.CRC32C (
 
   CRC32C(..),

src/Database/LSMTree/Internal/RunBuilder.hs

@@ -285,6 +285,8 @@ copyBlob ::
 copyBlob builder@RunBuilder {..} blobref = do
     blob <- BlobRef.readRawBlobRef runBuilderHasFS blobref
     writeBlob builder blob
+    --TODO: consier adding write blob functions to BlobFile
+    -- variants: at offset, at file pointer with CRC update.
 
 {-# SPECIALISE writeFilter ::
      RunBuilder IO h