treewide: remove cache.h inclusion due to previous changes

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/tree-diff.c b/tree-diff.c
index a76e6da..9ea2dd7 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -1,7 +1,7 @@
 /*
  * Helper functions for tree diff generation
  */
-#include "cache.h"
+#include "git-compat-util.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "tree.h"