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/commit-graph.c

@@ -1,5 +1,4 @@
 #include "builtin.h"
-#include "commit.h"
 #include "config.h"
 #include "dir.h"
 #include "environment.h"
@@ -9,7 +8,7 @@
 #include "parse-options.h"
 #include "repository.h"
 #include "commit-graph.h"
-#include "object-store-ll.h"
+#include "object-store.h"
 #include "progress.h"
 #include "replace-object.h"
 #include "tag.h"