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/citra.cpp

@@ -71,6 +71,7 @@ int main(int argc, char **argv) {
     EmuWindow_GLFW* emu_window = new EmuWindow_GLFW;
 
     VideoCore::g_hw_renderer_enabled = Settings::values.use_hw_renderer;
+    VideoCore::g_shader_jit_enabled = Settings::values.use_shader_jit;
 
     System::Init(emu_window);