Ensure Vulkan loader magic number persists in objects pooled by MoltenVK.

MVKDispatchableVulkanAPIObject::getVkHandle() re-establishes the loader magic number
before returning, in case the loader overwrote it before returning the object.

Docs/Whats_New.md

@@ -19,6 +19,7 @@ MoltenVK 1.0.37
 Released TBD
 
 - Revert to supporting host-coherent memory for linear images on macOS.
+- Ensure Vulkan loader magic number is set every time before returning any dispatchable Vulkan handle.
 
 
 

MoltenVK/MoltenVK/GPUObjects/MVKVulkanAPIObject.h

@@ -122,21 +122,30 @@ class MVKDispatchableVulkanAPIObject : public MVKVulkanAPIObject {
 public:
 
     /**
-     * Returns a reference to this object suitable for use as a Vulkan API handle.
-     * This is the compliment of the getDispatchableObject() method.
+     * Returns a reference to this object suitable for use as a dispatchable Vulkan API handle.
+	 *
+	 * Establishes the loader magic number every time, in case the loader
+	 * overwrote it for some reason before passing the object back,
+	 * particularly in pooled objects that the loader might consider freed.
+	 *
+	 * This is the compliment of the getDispatchableObject() function.
      */
-    void* getVkHandle() override { return &_icdRef; }
+    void* getVkHandle() override {
+		set_loader_magic_value(&_icdRef);
+		return &_icdRef;
+	}
 
     /**
      * Retrieves the MVKDispatchableVulkanAPIObject instance referenced by the dispatchable Vulkan handle.
-     * This is the compliment of the getVkHandle() method.
+	 *
+     * This is the compliment of the getVkHandle() function.
      */
     static inline MVKDispatchableVulkanAPIObject* getDispatchableObject(void* vkHandle) {
 		return vkHandle ? ((MVKDispatchableObjectICDRef*)vkHandle)->mvkObject : nullptr;
     }
 
 protected:
-    MVKDispatchableObjectICDRef _icdRef = { ICD_LOADER_MAGIC, this };
+    MVKDispatchableObjectICDRef _icdRef = { VK_NULL_HANDLE, this };
 
 };