Shader: Initial implementation of x86_x64 JIT compiler for Pica vertex shaders.

- Config: Add an option for selecting to use shader JIT or interpreter.
- Qt: Add a menu option for enabling/disabling the shader JIT.

src/citra_qt/main.h

@@ -70,6 +70,7 @@ private slots:
     void OnConfigure();
     void OnDisplayTitleBars(bool);
     void SetHardwareRendererEnabled(bool);
+    void SetShaderJITEnabled(bool);
     void ToggleWindowMode();
 
 private: