Fix OpenXR swapchain image usage flags

Author: janhsimon

src/Headset.cpp

@@ -290,7 +290,7 @@ Headset::Headset(const Context* context) : context(context)
     swapchainCreateInfo.arraySize = static_cast<uint32_t>(eyeCount);
     swapchainCreateInfo.faceCount = 1u;
     swapchainCreateInfo.mipCount = 1u;
-    swapchainCreateInfo.usageFlags = XR_SWAPCHAIN_USAGE_COLOR_ATTACHMENT_BIT;
+    swapchainCreateInfo.usageFlags = XR_SWAPCHAIN_USAGE_COLOR_ATTACHMENT_BIT | XR_SWAPCHAIN_USAGE_TRANSFER_SRC_BIT;
 
     result = xrCreateSwapchain(session, &swapchainCreateInfo, &swapchain);
     if (XR_FAILED(result))