b7fff5926b
The `php_preamble`/`php_system_block` combo has builtin low-hanging evasion for PHP's `disabled_functions` configuration (eg. `system` might not be available but `shell_exec` is), so use it instead of hardcoding `system`. This commit also brings modules/payloads/singles/php/reverse_perl.rb's style more in line with the other uses of `php_preamble`/`php_system_block`. Oh, and it makes lib/msf/core/payload/php.rb work on older Ruby version as well. Co-authored-by: Valentin Lobstein <88535377+Chocapikk@users.noreply.github.com>