Initialize pointer members in VulkanManager to null

Test: manual local testing

Change-Id: If81db17858354844b96677137cf67449dd91854b
diff --git a/libs/hwui/renderthread/VulkanManager.h b/libs/hwui/renderthread/VulkanManager.h
index b9898a7..c319c9e 100644
--- a/libs/hwui/renderthread/VulkanManager.h
+++ b/libs/hwui/renderthread/VulkanManager.h
@@ -59,11 +59,11 @@
     VkSurfaceKHR mVkSurface = VK_NULL_HANDLE;
     VkSwapchainKHR mSwapchain = VK_NULL_HANDLE;
 
-    BackbufferInfo* mBackbuffers;
+    BackbufferInfo* mBackbuffers = nullptr;
     uint32_t mCurrentBackbufferIndex;
 
     uint32_t mImageCount;
-    VkImage* mImages;
+    VkImage* mImages = nullptr;
     ImageInfo* mImageInfos;
     uint16_t mCurrentTime = 0;
 };