fmpz_mpoly_factor_lcc_wang

Wang's leading coefficient determination [Wan1978]. Given the irreducible factorisation lcAfac of the leading coefficient of $A$ in $x_0$ and the factorisation $\mathit{Auc} \prod_{i < r} \mathit{Auf}_i$ of $A(x_0, \alpha)$, sets lc_divs[i] to the predicted leading coefficient of the $i$-th factor of $A$: the product of the powers of the factors of the leading coefficient whose values at $\alpha$ divide the leading coefficient of $\mathit{Auf}_i$, times an integer. Returns 0 if the evaluation point fails Wang's condition, that each factor of the leading coefficient evaluates to an integer with a prime divisor not dividing $\mathit{Auc}$ times the constant and the values of the other factors.