Revert "Merge branch 'en/header-split-cache-h-part-3' into next"

This reverts commit 76ebce0b7a,
reversing changes made to 62e19d66fb,
in preparation for redoing the topic to make it buildable from the
source.

builtin/unpack-objects.c

@@ -1,11 +1,12 @@
 #include "builtin.h"
+#include "cache.h"
 #include "bulk-checkin.h"
 #include "config.h"
 #include "environment.h"
 #include "gettext.h"
 #include "git-zlib.h"
 #include "hex.h"
-#include "object-store-ll.h"
+#include "object-store.h"
 #include "object.h"
 #include "delta.h"
 #include "pack.h"