Create command buffers when rented rather than in advance (#31)

* Make it less likely to freeze, but the creation of the command buffer should probably be moved

* Create command buffers as they're rented rather than in advance

src/Ryujinx.Graphics.Metal/MetalRenderer.cs

@@ -41,7 +41,7 @@ namespace Ryujinx.Graphics.Metal
                 throw new NotSupportedException("Metal backend requires Tier 2 Argument Buffer support.");
             }
 
-            _queue = _device.NewCommandQueue(CommandBufferPool.MaxCommandBuffers);
+            _queue = _device.NewCommandQueue(CommandBufferPool.MaxCommandBuffers + 1);
             BackgroundQueue = _device.NewCommandQueue(CommandBufferPool.MaxCommandBuffers);
 
             _getMetalLayer = metalLayer;