a few include-what-you-use fixes

Summary: These headers don't include everything they use so things build now because of rando include orders and transitive inclusion. Breaks when attempting to build with clang modules.

Reviewed By: shixiao

Differential Revision: D8954753

fbshipit-source-id: d222370f17594f5c6aeccd21cbfd61bd8102245a

folly/detail/GroupVarintDetail.h

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <stddef.h>
+#include <stdint.h>
 
 namespace folly {
 

folly/executors/task_queue/BlockingQueue.h

@@ -15,6 +15,7 @@
  */
 #pragma once
 
+#include <chrono>
 #include <exception>
 #include <stdexcept>
 

folly/fibers/BoostContextCompatibility.h

@@ -36,6 +36,8 @@
  * https://github.com/boostorg/context/blob/boost-1.61.0/include/boost/context/detail/fcontext.hpp
  */
 
+#include <folly/Function.h>
+
 namespace folly {
 namespace fibers {