SCTP: Stopped accepting SSRCs higher than max.
Seems to fix asan-related crash.

BUG=https://code.google.com/p/chromium/issues/detail?id=570261

Review URL: https://codereview.webrtc.org/1571853002

Cr-Commit-Position: refs/heads/master@{#11205}
diff --git a/talk/media/sctp/sctpdataengine.cc b/talk/media/sctp/sctpdataengine.cc
index 94f242a..3753cd2 100644
--- a/talk/media/sctp/sctpdataengine.cc
+++ b/talk/media/sctp/sctpdataengine.cc
@@ -729,7 +729,13 @@
   }
 
   const uint32_t ssrc = stream.first_ssrc();
-  if (open_streams_.find(ssrc) != open_streams_.end()) {
+  if (ssrc >= cricket::kMaxSctpSid) {
+    LOG(LS_WARNING) << debug_name_ << "->Add(Send|Recv)Stream(...): "
+                    << "Not adding data stream '" << stream.id
+                    << "' with ssrc=" << ssrc
+                    << " because stream ssrc is too high.";
+    return false;
+  } else if (open_streams_.find(ssrc) != open_streams_.end()) {
     LOG(LS_WARNING) << debug_name_ << "->Add(Send|Recv)Stream(...): "
                     << "Not adding data stream '" << stream.id
                     << "' with ssrc=" << ssrc