avio: Only do implicit network initialization for network protocols

The implicit network initialization is set to be removed in the
future, but is kept for compatibility. By not doing the implicit
initialization for non-network protocols, we avoid the warning
about avformat_network_init() not being called for these, where
it really doesn't make much sense.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/avio.c

@@ -129,7 +129,7 @@ static int url_alloc_for_protocol (URLContext **puc, struct URLProtocol *up,
     int err;
 
 #if CONFIG_NETWORK
-    if (!ff_network_init())
+    if (up->flags & URL_PROTOCOL_FLAG_NETWORK && !ff_network_init())
         return AVERROR(EIO);
 #endif
     uc = av_mallocz(sizeof(URLContext) + strlen(filename) + 1);
@@ -159,7 +159,8 @@ static int url_alloc_for_protocol (URLContext **puc, struct URLProtocol *up,
  fail:
     *puc = NULL;
 #if CONFIG_NETWORK
-    ff_network_close();
+    if (up->flags & URL_PROTOCOL_FLAG_NETWORK)
+        ff_network_close();
 #endif
     return err;
 }
@@ -380,7 +381,8 @@ int ffurl_close(URLContext *h)
     if (h->is_connected && h->prot->url_close)
         ret = h->prot->url_close(h);
 #if CONFIG_NETWORK
-    ff_network_close();
+    if (h->prot->flags & URL_PROTOCOL_FLAG_NETWORK)
+        ff_network_close();
 #endif
     if (h->prot->priv_data_size) {
         if (h->prot->priv_data_class)