treewide: be explicit about dependence on convert.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>

streaming.c

@@ -2,6 +2,7 @@
  * Copyright (c) 2011, Google Inc.
  */
 #include "cache.h"
+#include "convert.h"
 #include "environment.h"
 #include "streaming.h"
 #include "repository.h"