Support Swoole v4.5.9 with PHP 8.0.0

[abraaoz]

Are there any intentions of making this extension compatible with Swoole v4.5.9 + PHP 8.0.0? When I execute the "make" command, the following appears:

In file included from /tmp/ext-async/swoole_async.cc:17:
/tmp/ext-async/php_swoole_async.h: In function ‘int sw_call_user_function_ex(HashTable*, zval*, zval*, zval**, uint32_t, zval*, int, HashTable*)’:
/tmp/ext-async/php_swoole_async.h:76:11: error: ‘call_user_function_ex’ was not declared in this scope; did you mean ‘sw_call_user_function_ex’?