librdf_redland: Fix db dependency

This fixes a regression introduced in 4b06383.

[dezgeg squashed in to fit the changes introduced in "db: Use more
conventional outputs, also split bin"]

pkgs/development/libraries/librdf/redland.nix

@@ -28,7 +28,10 @@ stdenv.mkDerivation rec {
 
   configureFlags =
     [ "--with-threads" ]
-    ++ stdenv.lib.optional withBdb "--with-bdb=${db}";
+    ++ stdenv.lib.optionals withBdb [
+      "--with-bdb-include=${db.dev}/include"
+      "--with-bdb-lib=${db.out}/lib"
+    ];
 
   # Fix broken DT_NEEDED in lib/redland/librdf_storage_sqlite.so.
   NIX_CFLAGS_LINK = "-lraptor2";