This update for php7-APCu fixes the following issues:

php7-APCu was updated to version 5.1.18:

- Fixed compatibility with PHP 7.4 and PHP 8.0
- Implement apcu_inc() and apcu_dec() using atomic operations. 
  This means that these functions no longer have to acquire a write lock. 
  These functions will now wraparound on overflow, 
  instead of saturating to a floating point value.
- Make table header in apc.php sticky.
- Fix compile warnings related to mktemp() usage.
- Fix compatibility with PHP 8.0.
- Fix required number of arguments for apcu_store() returned by Reflection.