Use folly::cacheline_align_v for cache alignment in thread pools

Summary:
Use folly::cacheline_align_v to prevent failures when running folly on platforms
where extended alignment is not supported.  The thread pools only used extended
alignment as an optimization; so it is safe to disable it when not needed

Reviewed By: yfeldblum

Differential Revision: D17077439

fbshipit-source-id: 63ba59aaf7ce45231bb25427af84292c3a3464a9

folly/executors/IOThreadPoolExecutor.h

@@ -73,8 +73,7 @@ class IOThreadPoolExecutor : public ThreadPoolExecutor, public IOExecutor {
   folly::EventBaseManager* getEventBaseManager();
 
  private:
-  struct alignas(hardware_destructive_interference_size) IOThread
-      : public Thread {
+  struct alignas(folly::cacheline_align_v) IOThread : public Thread {
     IOThread(IOThreadPoolExecutor* pool)
         : Thread(pool), shouldRun(true), pendingTasks(0) {}
     std::atomic<bool> shouldRun;

folly/executors/ThreadPoolExecutor.h

@@ -167,8 +167,7 @@ class ThreadPoolExecutor : public DefaultKeepAliveExecutor {
 
   struct TaskStatsCallbackRegistry;
 
-  struct alignas(hardware_destructive_interference_size) Thread
-      : public ThreadHandle {
+  struct alignas(folly::cacheline_align_v) Thread : public ThreadHandle {
     explicit Thread(ThreadPoolExecutor* pool)
         : id(nextId++),
           handle(),