Fix missing headers exposed by modular builds

Reviewed By: luciang

Differential Revision: D22555074

fbshipit-source-id: b853730e5d0dd96b6f94d71e2332653a1a44c9a1

folly/fibers/async/Promise.h

@@ -16,7 +16,9 @@
 
 #pragma once
 
+#include <folly/fibers/FiberManager.h>
 #include <folly/fibers/async/Async.h>
+#include <folly/fibers/traits.h>
 
 namespace folly {
 namespace fibers {

folly/lang/CArray.h

@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include <cstdlib>
+
 namespace folly {
 
 //  c_array

folly/lang/CustomizationPoint.h

@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include <type_traits>
+
 #include <folly/Portability.h>
 #include <folly/lang/StaticConst.h>
 

folly/memory/Arena-inl.h

@@ -20,6 +20,8 @@
 
 // Implementation of Arena.h functions
 
+#include <folly/lang/SafeAssert.h>
+
 namespace folly {
 
 template <class Alloc>