write-or-die.h: move declarations for write-or-die.c functions from cache.h

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/write-or-die.c b/write-or-die.c
index a7afc30..cc9e078 100644
--- a/write-or-die.c
+++ b/write-or-die.c
@@ -1,7 +1,8 @@
-#include "cache.h"
+#include "git-compat-util.h"
 #include "config.h"
 #include "run-command.h"
 #include "wrapper.h"
+#include "write-or-die.h"
 
 /*
  * Some cases use stdio, but want to flush after the write