solve_poly_inequality: real_roots sometimes sorted ascending, sometimes not

This only fails one test in sympy/solvers/tests/test_inequalities.py.
In all the other tests the roots of the polynomial are returned in ascending
order and need to be reversed in order to correctly build the intervals in
sympy.solvers.inequalities.solve_poly_inequality. For that one test, the roots
are returned in descending order and should not be reversed.