Fixed flv header to match specification.

Used "\x5" in 5th byte to claim presence of both audio and video.  Used
previous tag size 0 in the beginning of the flv body (bytes 10 .. 13) as
required by specification (see http://www.adobe.com/devnet/f4v.html).

Patch by Piotr Sikora.

src/http/modules/ngx_http_flv_module.c

@@ -23,7 +23,7 @@ static ngx_command_t  ngx_http_flv_commands[] = {
 };
 
 
-static u_char  ngx_flv_header[] = "FLV\x1\x1\0\0\0\x9\0\0\0\x9";
+static u_char  ngx_flv_header[] = "FLV\x1\x5\0\0\0\x9\0\0\0\0";
 
 
 static ngx_http_module_t  ngx_http_flv_module_ctx = {