Revert D5393697: [Folly] Add an sfmt19937 benchmark

Summary: This reverts commit bc725838dc7f62d030c7e68bc6d229042df2b46c

Differential Revision: D5393697

fbshipit-source-id: 4b9ef1e733b0ad73e6deea7ac8a52dfe785b4f2b

folly/test/RandomBenchmark.cpp

@@ -46,18 +46,6 @@ BENCHMARK(mt19937, n) {
   FOR_EACH_RANGE(i, 0, n) { doNotOptimizeAway(rng()); }
 }
 
-#if FOLLY_HAVE_EXTRANDOM_SFMT19937
-BENCHMARK(sfmt19937, n) {
-  BenchmarkSuspender braces;
-  std::random_device rd;
-  __gnu_cxx::sfmt19937 rng(rd());
-
-  braces.dismiss();
-
-  FOR_EACH_RANGE(i, 0, n) { doNotOptimizeAway(rng()); }
-}
-#endif
-
 BENCHMARK(threadprng, n) {
   BenchmarkSuspender braces;
   ThreadLocalPRNG tprng;