Support shared color mask, implement more shader instructions

Support shared color masks (used by Nouveau and maybe the NVIDIA
driver).
Support draw buffers (also required by OpenGL).
Support viewport transform disable (disabled for now as it breaks some
games).
Fix instanced rendering draw being ignored for multi draw.
Fix IADD and IADD3 immediate shader encodings, that was not matching
some ops.
Implement FFMA32I shader instruction.
Implement IMAD shader instruction.

Ryujinx.Graphics.Shader/StructuredIr/StructuredProgram.cs

@@ -171,6 +171,12 @@ namespace Ryujinx.Graphics.Shader.StructuredIr
             // decide which helper functions are needed on the final generated code.
             switch (operation.Inst)
             {
+                case Instruction.MultiplyHighS32:
+                    context.Info.HelperFunctionsMask |= HelperFunctionsMask.MultiplyHighS32;
+                    break;
+                case Instruction.MultiplyHighU32:
+                    context.Info.HelperFunctionsMask |= HelperFunctionsMask.MultiplyHighU32;
+                    break;
                 case Instruction.Shuffle:
                     context.Info.HelperFunctionsMask |= HelperFunctionsMask.Shuffle;
                     break;