Kill a couple of PThread includes

Summary: They aren't actually needed, and are in the way of being able to build Folly without PThread.

Reviewed By: yfeldblum

Differential Revision: D4882410

fbshipit-source-id: e4a48600f79c57bb965a35fab94962a29b8e06d4

folly/MicroSpinLock.h

@@ -42,7 +42,6 @@
 #include <type_traits>
 #include <boost/noncopyable.hpp>
 #include <cstdlib>
-#include <pthread.h>
 #include <mutex>
 #include <atomic>
 

folly/PicoSpinLock.h

@@ -44,7 +44,6 @@
 #include <cstdlib>
 #include <folly/Portability.h>
 #include <mutex>
-#include <pthread.h>
 #include <type_traits>
 
 #include <glog/logging.h>