Speculative fix for broken build on Mac bots. (#3527)

fml/platform/darwin/message_loop_darwin.mm

@@ -4,6 +4,7 @@
 
 #include "flutter/fml/platform/darwin/message_loop_darwin.h"
 
+#include <CoreFoundation/CoreFoundation.h>
 #include <Foundation/Foundation.h>
 
 namespace fml {

fml/thread.cc

@@ -4,6 +4,8 @@
 
 #include "flutter/fml/thread.h"
 
+#include <pthread.h>
+
 #include <memory>
 #include <string>
 
@@ -11,14 +13,6 @@
 #include "lib/ftl/build_config.h"
 #include "lib/ftl/synchronization/waitable_event.h"
 
-#if OS_MACOSX
-#include <pthread/pthread.h>
-#elif OS_LINUX || OS_ANDROID
-#include <pthread.h>
-#else
-#error Unsupported Platform
-#endif
-
 namespace fml {
 
 Thread::Thread(const std::string& name) : joined_(false) {