binomial._eval_Mod problems for composite modulus

[smichr]

>>> binomial(5, 3)
10
>>> [binomial(5,3)%i for i in range(9,18)]
[1, 0, 10, 10, 10, 10, 10, 10, 10]
>>> [binomial(5, 3, evaluate=False) % i for i in range(9,18)]
[3, 0, 10, 6, 10, 2, 0, 14, 10]
>>> list(range(9,18))
[9, 10, 11, 12, 13, 14, 15, 16, 17]

It appears to only be correct when the binomial value equals the modulus or when the modulus is prime.

[smichr]

This can be fixed by making sure that min(k, n - k) is selected when n > 0 and k > 0 and n - k > 0. I will add this to #18960.