avio: Add an URLProtocol flag for indicating that a protocol uses network

This definition is in two files, since the definitions will move
to the private header at the next bump.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/url.h

@@ -33,6 +33,7 @@
 
 #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 */
+#define URL_PROTOCOL_FLAG_NETWORK       2 /*< The protocol uses network */
 
 extern int (*url_interrupt_cb)(void);