Enable short header negotiation in fuzzers.

Change-Id: Ib777dcc80c7acd6dc1eda1c211b91e5428b83df1
Reviewed-on: https://boringssl-review.googlesource.com/12971
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <alangley@gmail.com>
diff --git a/fuzz/server.cc b/fuzz/server.cc
index 7cee0c7..1ee2ec9 100644
--- a/fuzz/server.cc
+++ b/fuzz/server.cc
@@ -240,6 +240,8 @@
 
     SSL_CTX_set_alpn_select_cb(ctx, ALPNSelectCallback, nullptr);
     SSL_CTX_set_next_protos_advertised_cb(ctx, NPNAdvertiseCallback, nullptr);
+
+    SSL_CTX_set_short_header_enabled(ctx, 1);
   }
 
   ~GlobalState() {