Disable the signal stack on Windows

Summary: There is no equivalent functionality for Windows, so disable it completely.

Reviewed By: andriigrynenko

Differential Revision: D3348481

fbshipit-source-id: 52a104f5a8013113f54d5b10c2f0f9b720eeb4f6

folly/fibers/FiberManager-inl.h

@@ -164,9 +164,11 @@ inline void FiberManager::runReadyFiber(Fiber* fiber) {
 }
 
 inline bool FiberManager::loopUntilNoReady() {
+#ifndef _WIN32
   if (UNLIKELY(!alternateSignalStackRegistered_)) {
     registerAlternateSignalStack();
   }
+#endif
 
   // Support nested FiberManagers
   auto originalFiberManager = this;

folly/fibers/FiberManager.cpp

@@ -277,6 +277,7 @@ static AsanUnpoisonMemoryRegionFuncPtr getUnpoisonMemoryRegionFunc() {
 
 #endif // FOLLY_SANITIZE_ADDRESS
 
+#ifndef _WIN32
 namespace {
 
 // SIGSTKSZ (8 kB on our architectures) isn't always enough for
@@ -333,5 +334,6 @@ void FiberManager::registerAlternateSignalStack() {
 
   alternateSignalStackRegistered_ = true;
 }
+#endif
 }
 }

folly/fibers/FiberManager.h

@@ -468,9 +468,11 @@ class FiberManager : public ::folly::Executor {
 
 #endif // FOLLY_SANITIZE_ADDRESS
 
+#ifndef _WIN32
   bool alternateSignalStackRegistered_{false};
 
   void registerAlternateSignalStack();
+#endif
 };
 
 /**