avio: make URL_PROTOCOL_FLAG_NESTED_SCHEME internal

libavformat/avio.h

@@ -136,10 +136,10 @@ void url_set_interrupt_cb(URLInterruptCB *interrupt_cb);
 #if FF_API_OLD_AVIO
 /* not implemented */
 attribute_deprecated int url_poll(URLPollEntry *poll_table, int n, int timeout);
-#endif
 
 
 #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
+#endif
 
 typedef struct URLProtocol {
     const char *name;

libavformat/url.h

@@ -26,6 +26,11 @@
 #define AVFORMAT_URL_H
 
 #include "avio.h"
+#include "libavformat/version.h"
+
+#if !FF_API_OLD_AVIO
+#define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
+#endif
 
 /**
  * Create a URLContext for accessing to the resource indicated by