ENH: update num_nnz in getCols regardless

[odow]

getCols only updates num_nnz if col_matrix_index or col_matrix_value is not NULL.

HiGHS/src/simplex/HighsSimplexInterface.cpp

Lines 562 to 569 in 2b89bd9

	if (col_matrix_index != NULL || col_matrix_value != NULL) {
	for (int el = lp.Astart_[out_from_col]; el < lp.Astart_[out_to_col + 1];
	el++) {
	if (col_matrix_index != NULL) col_matrix_index[num_nz] = lp.Aindex_[el];
	if (col_matrix_value != NULL) col_matrix_value[num_nz] = lp.Avalue_[el];
	num_nz++;
	}
	}

It should update num_nnz regardless, so that you can call it once to get the number of non-zeros, allocate the correct arrays, and then call it again (ala Gurobi and CPLEX).

This is useful for the Julia interface: jump-dev/HiGHS.jl#38 (comment)