shader/arithmetic_integer: Change IAdd to UAdd to avoid signed overflow

Signed integer addition overflow might be undefined behavior. It's free
to change operations to UAdd and use unsigned integers to avoid
potential bugs.

src/video_core/shader/decode/arithmetic_integer.cpp

@@ -40,12 +40,12 @@ u32 ShaderIR::DecodeArithmeticInteger(NodeBlock& bb, u32 pc) {
         op_a = GetOperandAbsNegInteger(op_a, false, instr.alu_integer.negate_a, true);
         op_b = GetOperandAbsNegInteger(op_b, false, instr.alu_integer.negate_b, true);
 
-        Node value = Operation(OperationCode::IAdd, op_a, op_b);
+        Node value = Operation(OperationCode::UAdd, op_a, op_b);
 
         if (instr.iadd.x) {
             Node carry = GetInternalFlag(InternalFlag::Carry);
             Node x = Operation(OperationCode::Select, std::move(carry), Immediate(1), Immediate(0));
-            value = Operation(OperationCode::IAdd, std::move(value), std::move(x));
+            value = Operation(OperationCode::UAdd, std::move(value), std::move(x));
         }
 
         if (instr.generates_cc) {