Do not attempt to read unused attribute, fix attributes count (#520)

Ryujinx.Graphics/Gal/Shader/GlslDecompiler.cs

@@ -878,7 +878,7 @@ namespace Ryujinx.Graphics.Gal.Shader
                 }
             }
 
-            if (DeclInfo.Index >= 16)
+            if (DeclInfo.Index >= 32)
             {
                 throw new InvalidOperationException($"Shader attribute offset {Abuf.Offs} is invalid.");
             }

Ryujinx.Graphics/Graphics3d/NvGpuEngine3d.cs

@@ -734,6 +734,11 @@ namespace Ryujinx.Graphics.Graphics3d
 
                 long VbPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.VertexArrayNAddress + ArrayIndex * 4);
 
+                if (VbPosition == 0)
+                {
+                    continue;
+                }
+
                 bool IsConst = ((Packed >> 6) & 1) != 0;
 
                 int Offset = (Packed >> 7) & 0x3fff;