Port fixes made by intern

[jiridanek]

Multiple repos at https://gitlab.cee.redhat.com/msgqe/qpid-*, e.g. https://gitlab.cee.redhat.com/msgqe/qpid-common-lib

[jiridanek]

In fact, there is more fixes in the main here than in those repos. Those repos only have code reorg and boost removal.

1. remove aac0 clients
2. remove the _MODERN thing
3. and we should be pretty much done, I guess