Require constant initialization for Yoga globals

Summary:
Require constant initialization for the layout generation counter and event subscriber list.

Changelog: [Internal]

___

landed-with-radar-review

Differential Revision: D127576224

Author: javache

packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp

@@ -35,7 +35,7 @@
 
 namespace facebook::yoga {
 
-std::atomic<uint32_t> gCurrentGenerationCount(0);
+constinit std::atomic<uint32_t> gCurrentGenerationCount(0);
 
 static bool hasAutoHorizontalMargin(const Style& style) {
   for (const auto direction : {Direction::LTR, Direction::RTL}) {

packages/react-native/ReactCommon/yoga/yoga/event/event.cpp

@@ -46,7 +46,7 @@ struct Node {
       : subscriber{std::move(subscriber)} {}
 };
 
-std::atomic<Node*> subscribers{nullptr};
+constinit std::atomic<Node*> subscribers{nullptr};
 
 Node* push(Node* newHead) {
   Node* oldHead = nullptr;