URI of HLS key can be relative, just like other URIs in the M3U8 file

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/stream_filter/httplive.c

@@ -775,7 +775,7 @@ static int parse_Key(stream_t *s, hls_stream_t *hls, char *p_read)
             if (end != NULL)
                 *end = 0;
         }
-        hls->psz_current_key_path = strdup(uri);
+        hls->psz_current_key_path = relative_URI(hls->url, uri);
         free(value);
 
         value = iv = parse_Attributes(p_read, "IV");