Hack fix Issue 10380 - [AA] Wrong code using associative array as key type in associative array

Issue URL: https://d.puremagic.com/issues/show_bug.cgi?id=10380

A correct fix is to replace `compare(a, b) == 0` with `equals(a, b)` in aaA (pull #522), but the pull was rejected because of planned switch to library AA implementation. Nevertheless wrong-code [Issue 10380](https://d.puremagic.com/issues/show_bug.cgi?id=10380) is what IMO should be closed as soon as possible. This pull fixes it.