倍精度関数型の境界条件の変数の値を読み込む。
call cg_iric_read_bc_functional(fid, type, num, name, x, y, ier)
ier = cg_iRIC_Read_BC_functional(fid, type, num, name, x, y);
x, y = cg_iRIC_Read_BC_functional(fid, type, num, name)