For supported types, static R/W globals unsafe code can be replaced by safe `Atomic*` types.
The pattern of usage is simple:
- AtomicBool#swap is used to fetch the old `KEYBOARD_HOOKED` value, while setting it to true;
- if the old value was true, there is effectively no change to `KEYBOARD_HOOKED`, and the flow exits from the enclosing function;
- if the old value was false, execute the function (the new `KEYBOARD_HOOKED` has been set to true by swap()).
The most conservative ordering is used, as the context is not performance-sensitive.
Atomics are not supported on every platform, but the project assumes x86-64, which supports them.
