backend_x64/a64_interface: Re-enable the constant folding pass

This was disabled for debugging, but never re-enabled. Just to be sure,
testing was done downstream in yuzu to make sure this didn't happen to
break anything (which seems to be the case).

src/backend/x64/a64_interface.cpp

@@ -203,6 +203,7 @@ private:
         IR::Block ir_block = A64::Translate(A64::LocationDescriptor{current_location}, get_code, {conf.define_unpredictable_behaviour});
         Optimization::A64CallbackConfigPass(ir_block, conf);
         Optimization::A64GetSetElimination(ir_block);
+        Optimization::ConstantPropagation(ir_block);
         Optimization::DeadCodeElimination(ir_block);
         Optimization::A64MergeInterpretBlocksPass(ir_block, conf.callbacks);
         // printf("%s\n", IR::DumpBlock(ir_block).c_str());