object-file.h: move declarations for object-file.c functions from cache.h

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -17,6 +17,7 @@
 #include "packfile.h"
 #include "protocol.h"
 #include "string-list.h"
+#include "object-file.h"
 #include "object-store.h"
 
 static struct trace_key trace_curl = TRACE_KEY_INIT(CURL);