ffserver: fix order of evaluation bugs

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit d40c0e4a6733ade9aaafc687bcaccc0cba1183b4)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
diff --git a/ffserver.c b/ffserver.c
index e7fdfbe..ab18d56 100644
--- a/ffserver.c
+++ b/ffserver.c
@@ -562,9 +562,11 @@
     default_port = 6000;
     for(stream = first_stream; stream != NULL; stream = stream->next) {
         if (stream->is_multicast) {
+            unsigned random0 = av_lfg_get(&random_state);
+            unsigned random1 = av_lfg_get(&random_state);
             /* open the RTP connection */
             snprintf(session_id, sizeof(session_id), "%08x%08x",
-                     av_lfg_get(&random_state), av_lfg_get(&random_state));
+                     random0, random1);
 
             /* choose a port if none given */
             if (stream->multicast_port == 0) {
@@ -3086,9 +3088,12 @@
  found:
 
     /* generate session id if needed */
-    if (h->session_id[0] == '\0')
+    if (h->session_id[0] == '\0') {
+        unsigned random0 = av_lfg_get(&random_state);
+        unsigned random1 = av_lfg_get(&random_state);
         snprintf(h->session_id, sizeof(h->session_id), "%08x%08x",
-                 av_lfg_get(&random_state), av_lfg_get(&random_state));
+                 random0, random1);
+    }
 
     /* find rtp session, and create it if none found */
     rtp_c = find_rtp_session(h->session_id);