replace for_each with range loops

No advantage over the latter, which is simpler.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/rpc/command_scheduler.cc

@@ -14,7 +14,8 @@
 namespace rpc {
 
 CommandScheduler::~CommandScheduler() {
-  std::for_each(begin(), end(), [](CommandSchedulerItem* item) { delete item; });
+  for (auto item : *this)
+    delete item;
 }
 
 CommandScheduler::iterator