Replace glFinish with barrier for WaitForIdle (#878)

Ryujinx.Graphics.GAL/IPipeline.cs

@@ -4,6 +4,8 @@ namespace Ryujinx.Graphics.GAL
 {
     public interface IPipeline
     {
+        void Barrier();
+
         void ClearRenderTargetColor(int index, uint componentMask, ColorF color);
 
         void ClearRenderTargetDepthStencil(

Ryujinx.Graphics.GAL/IRenderer.cs

@@ -18,8 +18,6 @@ namespace Ryujinx.Graphics.GAL
         ISampler CreateSampler(SamplerCreateInfo info);
         ITexture CreateTexture(TextureCreateInfo info);
 
-        void FlushPipelines();
-
         Capabilities GetCapabilities();
 
         ulong GetCounter(CounterType type);