make the code more readable

This way we can remove lots of #ifdef DEBUGs

also drop unused return code

that macro fits better here since there's no transport
specific code.

This has nothing to do with the transport.

Some of them are unused, some of them were missing. Also add a list of
the available debug macros.

Fixes ArcticaProject/nx-libs#825

no functional change

no functional change

turns out that our composite is much newer than xorg 6.9/7.0...

we don't have that...