add layer env var to hide present wait ext

layer/VkLayer_FROG_gamescope_wsi.cpp

@@ -183,6 +183,16 @@ namespace GamescopeWSILayer {
     return s_ensureMinImageCount;
   }
 
+  static bool getHidePresentWait() {
+    static bool s_hidePresentWait = []() -> bool {
+      if (auto hide = parseEnv<bool>("GAMESCOPE_WSI_HIDE_PRESENT_WAIT_EXT")) {
+        return *hide;
+      }
+      return false;
+    }();
+    return s_hidePresentWait;
+  }
+
   // Taken from Mesa, licensed under MIT.
   //
   // No real reason to rewrite this code,
@@ -588,7 +598,11 @@ namespace GamescopeWSILayer {
       createInfo.ppEnabledExtensionNames = enabledExts.data();
 
       setenv("vk_xwayland_wait_ready", "false", 0);
-      setenv("vk_khr_present_wait", "true", 0);
+      if (getHidePresentWait()) {
+        setenv("vk_khr_present_wait", "false", 0);
+      } else {
+        setenv("vk_khr_present_wait", "true", 0);
+      }
 
       VkResult result = pfnCreateInstanceProc(&createInfo, pAllocator, pInstance);
       if (result != VK_SUCCESS)
@@ -893,6 +907,10 @@ namespace GamescopeWSILayer {
       const vkroots::VkInstanceDispatch* pDispatch,
             VkPhysicalDevice             physicalDevice,
             VkPhysicalDeviceFeatures2*   pFeatures) {
+      if (getHidePresentWait()) {
+        fprintf(stderr, "[Gamescope WSI] Removing VkPhysicalDevicePresentWaitFeaturesKHR because GAMESCOPE_WSI_HIDE_PRESENT_WAIT_EXT is set\n");
+        vkroots::RemoveFromChain<VkPhysicalDevicePresentWaitFeaturesKHR>(pFeatures);
+      }
       pDispatch->GetPhysicalDeviceFeatures2(physicalDevice, pFeatures);
     }