Revert quad and long double precision drop in support

In the transition between sleef-3.5 and sleef-3.6, support
for quad and long precision was dropped.

This resulted in 4 funtions being removed from the ABI:

    [D] 'function const Sleef_longdouble2 Sleef_sincospil_u05(long double)'    {Sleef_sincospil_u05}
    [D] 'function const Sleef_longdouble2 Sleef_sincospil_u35(long double)'    {Sleef_sincospil_u35}
    [D] 'function const Sleef_quad2 Sleef_sincospiq_u05(Sleef_quad)'    {Sleef_sincospiq_u05}
    [D] 'function const Sleef_quad2 Sleef_sincospiq_u35(Sleef_quad)'    {Sleef_sincospiq_u35}

By reverting these changes and bring these functions back to the ABI.

This reverts commit 64c957fab5cf5db5d0445f8b47a063f48d0a13ac.