Results 1 issues of jsaf0

When building latest master (`53fded2`) with gcc 11.3 (Ubuntu 22.04) and `-Wall`, the compiler complains about mismatched new-delete warnings. See snippet below: ``` /home/jfp/async/test/async_for.cpp: In function ‘boost::async::generator test_data_gen()’: /home/jfp/async/test/async_for.cpp:30:1: warning:...