[php-src] Issue #12393: strtotime not returning false for the wrong string

Issue: https://github.com/php/php-src/issues/12393 Author: asmafarhat2006 ### Description The following code: ```php <?php $trimmed = 'MONDAY 2, Tuesday 2, Wednesday 3, Thursday 4, Friday 5'; var_dump(strtotime($trimmed)); $trimmed = 'Monday ,Tuesday , Wednesday'; var_dump(strtotime($trimmed)); ``` For first var_dump returns false which is correct but for second var_dump returns the UNIX timestamp which is incorrect It should return false when there are multiple days in week. which it does for the first example but doesnt for the 2nd. Affects all PHP versions 7.4+ ### PHP Version PHP 7.4+ ### Operating System _No response_