rtmpproto: Clear the flv allocation size on reallocp failures

This was overlooked in d872fb0f7 since I assumed all the realloc
issues in the rtmp code was fixed already.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rtmpproto.c

@@ -2098,8 +2098,10 @@ static int append_flv_data(RTMPContext *rt, RTMPPacket *pkt, int skip)
 
     old_flv_size = update_offset(rt, size);
 
-    if ((ret = av_reallocp(&rt->flv_data, rt->flv_size)) < 0)
+    if ((ret = av_reallocp(&rt->flv_data, rt->flv_size)) < 0) {
+        rt->flv_size = rt->flv_off = 0;
         return ret;
+    }
     bytestream2_init_writer(&pbc, rt->flv_data, rt->flv_size);
     bytestream2_skip_p(&pbc, old_flv_size);
     bytestream2_put_byte(&pbc, pkt->type);
@@ -2199,8 +2201,10 @@ static int handle_metadata(RTMPContext *rt, RTMPPacket *pkt)
 
     old_flv_size = update_offset(rt, pkt->size);
 
-    if ((ret = av_reallocp(&rt->flv_data, rt->flv_size)) < 0)
+    if ((ret = av_reallocp(&rt->flv_data, rt->flv_size)) < 0) {
+        rt->flv_size = rt->flv_off = 0;
         return ret;
+    }
 
     next = pkt->data;
     p    = rt->flv_data + old_flv_size;