avformat/rtsp: initialize reply1

It seems reply1 is initialized by ff_rtsp_send_cmd() in most cases but there
are code paths like "continue" which look like they could skip it but even if not
writing this so a complex loop after several layers of calls initialized a local
variable through a pointer is just bad design.
This patch simply initialized the variable.

Fixes: CID1473532 Uninitialized scalar variable

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 498ce4e8b8)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/rtsp.c

@@ -1460,6 +1460,8 @@ int ff_rtsp_make_setup_request(AVFormatContext *s, const char *host, int port,
     char cmd[MAX_URL_SIZE];
     const char *trans_pref;
 
+    memset(&reply1, 0, sizeof(reply1));
+
     if (rt->transport == RTSP_TRANSPORT_RDT)
         trans_pref = "x-pn-tng";
     else if (rt->transport == RTSP_TRANSPORT_RAW)