PHP, 39 38 bytes

<?=($n=$argv[1])&PHP_INT_MIN?-1:1-!$n;

Not using comparison operators. Should work on most systems.

PHP_INT_MIN has only one bit set: the most significant one. If this is set in the input, the input is negative. !$n casts to integer, evaluates to 0 for positive values and 1 for 0.