Vulkan: Simplify MultiFenceHolder and managing them (#4845)

* Vulkan: Simplify waitable add/remove

Removal of unnecessary hashset and dictionary

* Thread safety for GetBufferData in PersistentFlushBuffer

* Fix WaitForFencesImpl thread safety

* Proper methods for risky reference increments

* Wrong type of CB.

* Address feedback

src/Ryujinx.Graphics.Vulkan/FenceHolder.cs

@@ -32,6 +32,25 @@ namespace Ryujinx.Graphics.Vulkan
             return _fence;
         }
 
+        public bool TryGet(out Fence fence)
+        {
+            int lastValue;
+            do
+            {
+                lastValue = _referenceCount;
+
+                if (lastValue == 0)
+                {
+                    fence = default;
+                    return false;
+                }
+            }
+            while (Interlocked.CompareExchange(ref _referenceCount, lastValue + 1, lastValue) != lastValue);
+
+            fence = _fence;
+            return true;
+        }
+
         public Fence Get()
         {
             Interlocked.Increment(ref _referenceCount);