lib_enc/lp_exc_e_fx.c : restore shl_o in corr_xy1_fx()

        xy = shr( xy, 1 );      /* be sure that xy < yy */

        gain = div_s( xy, yy ); // Q15

        i = sub( exp_xy, exp_yy );

#ifdef ISSUE_1796_replace_shl_o

        gain = shl_sat( gain, i ); /* saturation can occur here */

        /*

                Theres only one x, to solve 32767 = x * 2 ^ y, if y is an integer : x = 32767 and y = 0 .

                So we can assume a saturated overflow, if gain == 32767 and one of the two conditions is false: x == 32767 or y == 0

        */

        test();

        IF( gain == MAX_16 && i != 0 )

        {

            Overflow = 1;

        }

#else

        gain = shl_o( gain, i, &Overflow ); /* saturation can occur here */

#endif

        *Overflow_out |= Overflow;

        move16();