remove asserts in mpoly_pack_vec
remove asserts in mpoly_pack_vec

wbhart/flint2,fredrik-johansson/flint2,wbhart/flint2,dsroche/flint2,dsroche/flint2,dsroche/flint2,fredrik-johansson/flint2,wbhart/flint2,fredrik-johansson/flint2,dsroche/flint2