Include <folly/portability/PThread.h> where needed

Summary: Diff #11 of 14.

Reviewed By: mzlee

Differential Revision: D3262478

fbshipit-source-id: d06eee44d1ccefc78a381e44c400c0242b5e0e5a

folly/detail/MemoryIdler.h

@@ -22,6 +22,7 @@
 #include <folly/Hash.h>
 #include <folly/Traits.h>
 #include <folly/detail/Futex.h>
+#include <folly/portability/PThread.h>
 
 namespace folly {
 

folly/io/async/EventBase.h

@@ -42,6 +42,7 @@
 #include <folly/io/async/AsyncTimeout.h>
 #include <folly/io/async/Request.h>
 #include <folly/io/async/TimeoutManager.h>
+#include <folly/portability/PThread.h>
 #include <glog/logging.h>
 
 #include <event.h>  // libevent