Remove dead includes in folly/executors

Reviewed By: yfeldblum

Differential Revision: D18528940

fbshipit-source-id: 288abb510535540698416ac046c1057e110e4478

folly/executors/test/TimekeeperScheduledExecutorTest.cpp

@@ -25,18 +25,8 @@
 #include <folly/portability/GTest.h>
 #include <folly/synchronization/Baton.h>
 
-using folly::Duration;
-using folly::Executor;
-using folly::Func;
-using folly::Future;
 using folly::ManualTimekeeper;
-using folly::Promise;
-using folly::ScheduledExecutor;
-using folly::SemiFuture;
 using folly::TimekeeperScheduledExecutor;
-using folly::Unit;
-using std::chrono::steady_clock;
-using time_point = steady_clock::time_point;
 
 namespace {
 void simpleTest(std::unique_ptr<folly::Executor> const& parent) {