Bug in Cbc_isProvenInfeasible() and in Cbc_isProvenOptimal() functions using C API

[AndreaB2604]

I found a minor bug in the Cbc_isProvenInfeasible() and in the Cbc_isProvenOptimal(). If I try to solve a model, the functions work correctly, but if I add new constraints that make the problem infeasible and solve it again, the functions return the same values as before and they should be swapped. On the other hand the log printed in output are right. I hope this information will be helpful.