Fix zend_result return values

[MaxKellermann]

1 is not a legal zend_result.

[MaxKellermann]

Note that in PHP-8.1, ext/curl doesn't yet use zend_result; it was refactored in commit 5ad1b89 (@Girgias), but the wrong return value was not fixed in that commit.

[Girgias]

Those zend_ini changes feels like a bug I introduced in: fa8d9b1 where I should have used bool. Which didn't cause any issue because out of the only two cases where this function is used, only one checks the return value and explicitly checks for == 0.