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>

builtin/hash-object.c

@@ -15,6 +15,7 @@
 #include "parse-options.h"
 #include "exec-cmd.h"
 #include "setup.h"
+#include "write-or-die.h"
 
 /*
  * This is to create corrupt objects for debugging and as such it