Remove extra FLAGS_seed definition

Summary: This is not used within the file.  Cleaning up.

Reviewed By: yfeldblum

Differential Revision: D2784500

fb-gh-sync-id: 60270cb20c40b79f988c5536fa00e0a0f1d08e46

folly/futures/test/BarrierTest.cpp

@@ -24,8 +24,6 @@
 #include <glog/logging.h>
 #include <gtest/gtest.h>
 
-DEFINE_int32(seed, 0, "Random seed");
-
 namespace folly { namespace futures { namespace test {
 
 TEST(BarrierTest, Simple) {