Shader_IR: Implement Fast BRX and allow multi-branches in the CFG.

src/video_core/shader/ast.cpp

@@ -228,7 +228,7 @@ public:
         inner += expr.value ? "true" : "false";
     }
 
-    void operator()(ExprGprEqual const& expr) {
+    void operator()(const ExprGprEqual& expr) {
         inner += "( gpr_" + std::to_string(expr.gpr) + " == " + std::to_string(expr.value) + ')';
     }