avio: deprecate av_url_read_pause

It's not used anywhere internally.

Salvage its documentation for ffio_read_pause.

libavformat/avio.c

@@ -388,12 +388,14 @@ void url_set_interrupt_cb(URLInterruptCB *interrupt_cb)
     url_interrupt_cb = interrupt_cb;
 }
 
+#if FF_API_OLD_AVIO
 int av_url_read_pause(URLContext *h, int pause)
 {
     if (!h->prot->url_read_pause)
         return AVERROR(ENOSYS);
     return h->prot->url_read_pause(h, pause);
 }
+#endif
 
 int64_t av_url_read_seek(URLContext *h,
         int stream_index, int64_t timestamp, int flags)

libavformat/avio.h

@@ -114,6 +114,7 @@ attribute_deprecated int64_t url_filesize(URLContext *h);
 attribute_deprecated int url_get_file_handle(URLContext *h);
 attribute_deprecated int url_get_max_packet_size(URLContext *h);
 attribute_deprecated void url_get_filename(URLContext *h, char *buf, int buf_size);
+attribute_deprecated int av_url_read_pause(URLContext *h, int pause);
 #endif
 
 /**
@@ -135,13 +136,6 @@ void url_set_interrupt_cb(URLInterruptCB *interrupt_cb);
 attribute_deprecated int url_poll(URLPollEntry *poll_table, int n, int timeout);
 #endif
 
-/**
- * Pause and resume playing - only meaningful if using a network streaming
- * protocol (e.g. MMS).
- * @param pause 1 for pause, 0 for resume
- */
-int av_url_read_pause(URLContext *h, int pause);
-
 /**
  * Seek to a given timestamp relative to some component stream.
  * Only meaningful if using a network streaming protocol (e.g. MMS.).

libavformat/avio_internal.h

@@ -66,6 +66,11 @@ uint64_t ffio_read_varlen(AVIOContext *bc);
 /** @warning must be called before any I/O */
 int ffio_set_buf_size(AVIOContext *s, int buf_size);
 
+/**
+ * Pause and resume playing - only meaningful if using a network streaming
+ * protocol (e.g. MMS).
+ * @param pause 1 for pause, 0 for resume
+ */
 int     ffio_read_pause(AVIOContext *h,    int pause);
 int64_t ffio_read_seek (AVIOContext *h,    int stream_index,
                         int64_t timestamp, int flags);